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uploading first time (#13)
* uploading first time * added few changes in ReadMe.md * corrected one solution file link Co-authored-by: Gourav Rusiya <[email protected]>
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‎C++/Count-Primes.cpp

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class Solution {
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public:
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int countPrimes(int n) {
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vector<bool> arr(n+1,0);
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arr[0]=true;
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arr[1]=true;
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for(int i=2;i*i<=n;i++){
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if(arr[i]==false){
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for(int j = i*i;j<=n;j+=i){
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arr[j]=true;
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}
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}
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}
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int count = 0;
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for(int i=2;i<n;i++){
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if(!arr[i]){
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count++;
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}
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}
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return count;
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}
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};

‎C++/Excel-Sheet-Column-Title.cpp

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/*
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* Runtime - 0ms
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* Memory - 5.8
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* LOGIC - simple maths
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*
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*/
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class Solution {
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public:
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string convertToTitle(int n) {
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string s="";
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while(n>26){
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int rem = n%26;
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n=n/26;
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if(rem==0){
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rem = 26;
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n--;
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}
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s.push_back('A'+(rem-1));
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}
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s.push_back('A'+n-1);
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reverse(s.begin(),s.end());
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return s;
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}
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};

‎C++/Reverse-Integer.cpp

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class Solution {
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public:
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int reverse(int x) {
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int rev = 0;
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while (x!=0) {
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int pop = x % 10;
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x /= 10;
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// to check that it may not overflow integer range
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if (rev > INT_MAX/10 || (rev == INT_MAX / 10 && pop > 7)) return 0;
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if (rev < INT_MIN/10 || (rev == INT_MIN / 10 && pop < -8)) return 0;
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rev = rev * 10 + pop;
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}
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return rev;
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}
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};
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‎C++/Sudoku-Solver.cpp

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/*
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* Runtime - 56ms
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* Memory - 6.8
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* LOGIC - described in functions
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*
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*/
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class Solution {
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public:
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// to check whether num is valid in that row
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bool isRowSafe(vector<vector<char>>& board, int row, char num)
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{
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for(int col = 0;col<9;col++)
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{
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if(board[row][col] == num)
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return true;
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}
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return false;
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}
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// to check whether num is valid in that column
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bool isColumnSafe(vector<vector<char>>& board, int col , char num)
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{
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for(int row = 0; row<9; row++)
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{
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if(board[row][col] == num)
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return true;
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}
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return false;
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}
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// to check whether num is valid in that 3*3 matrix grid
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bool isBoxSafe(vector<vector<char>>& board, int row1, int col1 , char num)
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{
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for(int row = 0;row<3;row++)
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{
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for(int col = 0;col<3;col++)
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{
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if(board[row1 + row][col1 + col] == num)
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return true;
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}
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}
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return false;
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}
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bool isSafe(vector<vector<char>>& board, int row, int col , char num)
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{
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return !isRowSafe(board,row,num) && !isColumnSafe(board, col, num) && !isBoxSafe(board, row-row%3,col-col%3,num) && board[row][col] == '.';
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}
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bool findUnassignedLocation(vector<vector<char>>& board, int &row, int &col)
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{
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for(row = 0;row<9;row++)
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{
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for(col = 0;col<9;col++)
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{
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if(board[row][col] == '.')
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return true;
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}
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}
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return false;
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}
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bool solve(vector<vector<char>>& board)
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{
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int row,col;
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if(!findUnassignedLocation(board, row, col))
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return true;
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for(char i = '1' ; i<='9';i++)
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{
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if(isSafe(board,row,col,i))
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{
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board[row][col] = i;
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if(solve(board))
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return true;
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board[row][col] = '.';
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}
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}
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return false;
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}
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/* A utility function to print grid */
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void printGrid(vector<vector<char>>& board)
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{
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for (int row = 0; row < 9; row++) {
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for (int col = 0; col < 9; col++)
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cout << board[row][col] << " ";
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cout << endl;
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}
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}
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void solveSudoku(vector<vector<char>>& board) {
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solve(board);
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printGrid(board);
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}
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};
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‎Java/LRU-Cache.java

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/**
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* LRU Cache
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*
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* Logic : maintain doubly linked List for insertion at head and deletion from tail and maintain hashmap of key as key and value as node. Node consists of key, value, prev and next pointers.
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* Runtime: 16 ms
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* Memory Usage: 47.9 MB
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*/
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class LRUCache {
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final Node head = new Node();
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final Node tail = new Node();
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int capacity;
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Map<Integer, Node> map;
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public LRUCache(int capacity) {
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map = new HashMap(capacity);
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this.capacity = capacity;
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head.next = tail;
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tail.prev = head;
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}
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public int get(int key) {
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int result = -1;
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Node node = map.get(key);
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if(node!=null)
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{
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remove(node);
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add(node);
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result = node.val;
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}
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return result;
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}
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public void put(int key, int value) {
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Node node = map.get(key);
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if(node!=null)
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{
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remove(node);
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node.val = value;
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add(node);
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}
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else{
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if(map.size() == capacity)
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{
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map.remove(tail.prev.key);
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remove(tail.prev);
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}
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Node new_node = new Node();
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new_node.key = key;
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new_node.val = value;
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map.put(key, new_node);
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add(new_node);
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}
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}
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public void add(Node node)
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{
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Node head_next = head.next;
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node.next = head_next;
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head_next.prev = node;
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head.next = node;
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node.prev = head;
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}
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public void remove(Node node)
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{
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Node next_node = node.next;
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Node prev_node = node.prev;
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next_node.prev = prev_node;
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prev_node.next = next_node;
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}
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class Node{
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int key;
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int val;
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Node prev;
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Node next;
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}
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}
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/**
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* Your LRUCache object will be instantiated and called as such:
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* LRUCache obj = new LRUCache(capacity);
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* int param_1 = obj.get(key);
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* obj.put(key,value);
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*/

‎README.md

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</div>
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<br/>
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## String
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| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
@@ -128,13 +129,30 @@ Check out ---> [Sample PR](https://github.com/codedecks-in/LeetCode-Solutions/pu
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| --- | ------------------------------------------------------------- | --------------------------------- | ------ | ------ | ---------- | --- | ------------- |
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| 001 | [Two Sum](https://leetcode.com/problems/two-sum/)| [Java](./Java/two-sum.java) <br> [Python](./Python/1_TwoSum.py)|_O(N)_|_O(N)_|Easy|||
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| 242 | [Valid Anagram](https://leetcode.com/problems/valid-anagram/) | [Java](./Java/valid-anagram.java) | _O(n)_ | _O(1)_ | Easy | | Unicode chars|
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| 146 | [LRU Cache](https://leetcode.com/problems/lru-cache/) | [Java](./Java/LRU-Cache.java) | | | Medium | | |
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<br/>
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<div align="right">
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<b><a href="#algorithms">⬆️ Back to Top</a></b>
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</div>
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<br/>
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## Math
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| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
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| --- | ---------------------------------------------------------------- | --------------------------------------- | ---------- | ------ | ---------- | --------- | ---- |
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| 204 | [Count Primes](https://leetcode.com/problems/count-primes) | [C++](./C++/Count-Primes.cpp) | _O(n(log(logn)))_ | _O(n)_ | Easy | Math | |
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| 168 | [Excel Sheet Column Title](https://leetcode.com/problems/excel-sheet-column-title) |[C++](./C++/Excel-Sheet-Column-Title.cpp)| _O(n)_ | _O(n)_ | Easy | String| |
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| 7 | [Reverse Integer](https://leetcode.com/problems/reverse-integer) |[C++](./C++/Reverse-Integer.cpp) | _O(n)_ | _O(n)_ | Easy | Math | |
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<br/>
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<div align="right">
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<b><a href="#algorithms">⬆️ Back to Top</a></b>
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</div>
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<br/>
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## Two Pointer
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| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
@@ -147,6 +165,20 @@ Check out ---> [Sample PR](https://github.com/codedecks-in/LeetCode-Solutions/pu
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</div>
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<br/>
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## BackTracking
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| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
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| --- | --------------------------------------------------------------------- | ----------------------------------------- | ------ | ------ | ---------- | ----- | ---- |
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| 037 | [Sudoku Solver](https://leetcode.com/problems/sudoku-solver/) | [C++](./C++/Sudoku-Solver.cpp) | _O(9^(n*n))_ | _O(n*n)_ | Hard | Hash Table | |
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<br/>
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<div align="right">
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<b><a href="#algorithms">⬆️ Back to Top</a></b>
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</div>
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<br/>
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## Binary Search
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| # | Title | Solution | Time | Space | Difficulty | Tag | Note |
@@ -186,6 +218,7 @@ Check out ---> [Sample PR](https://github.com/codedecks-in/LeetCode-Solutions/pu
186218
| [Lokendra Bohra](https://github.com/lokendra1704/) <br> <img src="https://github.com/lokendra1704.png" width="100" height="100"> | India | Python | [Leetcode](https://t.co/u0OByxhcHA) <br> [Hackerrank](https://www.hackerrank.com/lokendra17) |
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| [Yuri Spiridonov](https://github.com/YuriSpiridonov) <br> <img src="https://github.com/YuriSpiridonov.png" width="100" height="100"> | Russia | Python | [Twitter](https://twitter.com/YuriSpiridonov)<br>[Leetcode](https://leetcode.com/yurispiridonov/)<br>[Hackerrank](https://www.hackerrank.com/YuriSpiridonov) |
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| [Naveen Kashyap](https://github.com/naveenkash) <br> <img src="https://github.com/naveenkash.png" width="100" height="100"> | India | Javascript | [Twitter](https://twitter.com/naveen_kashyapp)<br>[Leetcode](https://leetcode.com/naveenkash/) |
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| [Rudra Mishra](https://github.com/Rudra407) <br> <img src="https://github.com/Rudra407.png" width="100" height="100"> | India | C++ | [Twitter](https://twitter.com/ruDra_Mishra407)<br>[Leetcode](https://leetcode.com/rudramishra/) |
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| [Sachin Singh Negi](https://github.com/sachinnegi) <br> <img src="https://github.com/sachinnegi.png" width="100" height="100"> | India | Python | [Twitter](https://twitter.com/SachinSinghNe17)<br>[Leetcode](https://leetcode.com/negisachin688/)<br>[Hackerrrak](https://www.hackerrank.com/negisachin688) | |
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<br/>
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<div align="right">

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