471/500 problems solved

Author: kaidul

Beautiful_Arrangement.cpp

@@ -0,0 +1,23 @@
+class Solution {
+    int countArrangement(int indx, int mask, const int N, vector<vector<int>>& dp) {
+        if(indx > N) {
+            return 1;
+        }
+        if(dp[indx][mask] != -1) {
+            return dp[indx][mask];
+        }
+        int ret = 0;
+        for(int i = 1; i <= N; i++) {
+            if(!(mask & (1 << i)) and (indx % i == 0 or i % indx == 0)) {
+                ret += countArrangement(indx + 1, mask | (1 << i), N, dp);
+            }
+        }
+        return dp[indx][mask] = ret;
+    }
+    
+public:
+    int countArrangement(int N) {
+        vector<vector<int>> dp(N + 1, vector<int>((1 << N) << 1, -1));
+        return countArrangement(1, 0, N, dp);
+    }
+};

Contiguous_Array.cpp

@@ -0,0 +1,20 @@
+class Solution {
+public:
+    int findMaxLength(vector<int>& arr) {
+        unordered_map<int, int> dp;
+        int one = 0, zero = 0;
+        dp[0] = -1;
+        int result = 0;
+        for(int i = 0; i < (int)arr.size(); i++) {
+            one += arr[i];
+            zero += !arr[i];
+            if(dp.count(one - zero)) {
+                result = max(result, i - dp[one - zero]);
+            } else {
+                dp[one - zero] = i;
+            }
+        }
+        
+        return result;
+    }
+};

Detect_Capital.cpp

@@ -0,0 +1,26 @@
+class Solution {
+public:
+    bool detectCapitalUse(string word) {
+        int n = (int)word.length();
+        if(n <= 1) return true;
+        bool firstUpper = false;
+        if(isupper(word[0])) {
+            firstUpper = true;
+        }
+        bool allUpper = true, allLower = true;
+        for(int i = 1; i < n; i++) {
+            if(isupper(word[i])) {
+                allLower = false;
+            } else {
+                allUpper = false;
+            }
+        }
+        if(!allUpper and !allLower) {
+            return false;
+        }
+        if(firstUpper) {
+            return true;
+        }
+        return allLower;
+    }
+};