update

Author: ThanhNIT

src/main/java/g0101_0200/s0139_word_break/Solution.java

@@ -5,30 +5,33 @@
 // #Dynamic_Programming_I_Day_9 #Udemy_Dynamic_Programming #Big_O_Time_O(M+max*N)_Space_O(M+N+max)
 // #2024_11_15_Time_1_ms_(99.42%)_Space_42.1_MB_(80.42%)
 
-import java.util.HashSet;
 import java.util.List;
-import java.util.Set;
 
 public class Solution {
-    Boolean[] memo;
+    private Boolean[] memo;
+
     public boolean wordBreak(String s, List<String> wordDict) {
         memo = new Boolean[s.length() + 1];
         return dp(s, 0, wordDict);
     }
 
-    public boolean dp(String s, int i, List<String> wordDict){
-        if(i == s.length()) return true;
-        if(memo[i] != null) return memo[i];
-        for(String word: wordDict){
+    public boolean dp(String s, int i, List<String> wordDict) {
+        if (i == s.length()) {
+            return true;
+        }
+        if (memo[i] != null) {
+            return memo[i];
+        }
+        for (String word : wordDict) {
             int len = word.length();
-            if(i + len > s.length()){
+            if (i + len > s.length()) {
                 continue;
             }
             String subStr = s.substring(i, i + len);
-            if(!subStr.equals(word)){
+            if (!subStr.equals(word)) {
                 continue;
             }
-            if(dp(s, i + len, wordDict)){
+            if (dp(s, i + len, wordDict)) {
                 memo[i] = true;
                 return true;
             }

src/main/java/g0101_0200/s0152_maximum_product_subarray/Solution.java

@@ -6,19 +6,20 @@
 
 public class Solution {
     public int maxProduct(int[] nums) {
-        int m=Integer.MIN_VALUE;
-        int n=nums.length;
-        int start=1;
-        int end=1;
-        for(int i=0;i<n;i++){
-            if(start==0)
-                start=1;
-            if (end==0)
-                end=1;
-            start=start*nums[i];
-            end=end*nums[n-i-1];
-            m=Math.max(m,Math.max(start,end));
-
+        int m = Integer.MIN_VALUE;
+        int n = nums.length;
+        int start = 1;
+        int end = 1;
+        for (int i = 0; i < n; i++) {
+            if (start == 0) {
+                start = 1;
+            }
+            if (end == 0) {
+                end = 1;
+            }
+            start = start * nums[i];
+            end = end * nums[n - i - 1];
+            m = Math.max(m, Math.max(start, end));
         }
         return m;
     }

src/main/java/g0201_0300/s0208_implement_trie_prefix_tree/Trie.java

@@ -5,116 +5,102 @@
 // #Big_O_Time_O(word.length())_or_O(prefix.length())_Space_O(N)
 // #2024_11_15_Time_30_ms_(99.78%)_Space_55.1_MB_(72.51%)
 
+import java.util.Arrays;
+
 @SuppressWarnings("java:S1104")
 public class Trie {
-    boolean ans=false;
-    TrieNode[] trees=new TrieNode[26];
-    public Trie() {
-
-    }
+    private boolean ans = false;
+    private final TrieNode[] trees = new TrieNode[26];
+    public Trie() {}
 
-    TrieNode mapWordToTree(TrieNode t, String word, int i){
-        char m=word.charAt(i);
-        boolean found=false;
-        TrieNode a=t.nexts[m-'a'];
-        if(a!=null){
-            if(i!=word.length()-1){
-                mapWordToTree(a,word,i+1);
-                found=true;
-
-            }else{
-                a.end=true;
-                found=true;
+    TrieNode mapWordToTree(TrieNode t, String word, int i) {
+        char m = word.charAt(i);
+        boolean found = false;
+        TrieNode a = t.nexts[m - 'a'];
+        if (a != null) {
+            if (i != word.length() - 1) {
+                mapWordToTree(a, word, i + 1);
+            } else {
+                a.end = true;
             }
+            found = true;
         }
-        if(!found){
-            TrieNode prev=t;
-            for(int j=i;j<word.length();j++){
-                TrieNode temp=new TrieNode(word.charAt(j));
-                prev.nexts[word.charAt(j)-'a']=temp;
-                prev=temp;
+        if (!found) {
+            TrieNode prev = t;
+            for (int j = i; j < word.length(); j++) {
+                TrieNode temp = new TrieNode(word.charAt(j));
+                prev.nexts[word.charAt(j) - 'a'] = temp;
+                prev = temp;
             }
-            prev.end=true;
+            prev.end = true;
         }
         return t;
     }
 
     public void insert(String word) {
-        char a=word.charAt(0);
-        if(trees[a-'a']==null){
-            TrieNode t=new TrieNode(a);
-            trees[a-'a']=t;
-            if(1==word.length()){
-                trees[a-'a'].end=true;
-                return;
-            }
-            trees[a-'a']=mapWordToTree(trees[a-'a'],word,1);
-        }else{
-            if(1==word.length()){
-                trees[a-'a'].end=true;
-                return;
-            }
-            trees[a-'a']=mapWordToTree(trees[a-'a'],word,1);
+        char a = word.charAt(0);
+        if (trees[a - 'a'] == null) {
+            TrieNode t = new TrieNode(a);
+            trees[a - 'a'] = t;
+        }
+        if (1 == word.length()) {
+            trees[a - 'a'].end = true;
+            return;
         }
-        //System.out.println(trees[a-'a']);
+        trees[a - 'a'] = mapWordToTree(trees[a - 'a'], word, 1);
     }
-    public boolean searchWordInTree(TrieNode t, String word, int i){
-        char a=word.charAt(i);
-        TrieNode m=t.nexts[a-'a'];
-        if(m!=null){
 
-            if(i==word.length()-1){
-                ans=true;
-                if(m.end){
-                    return true;
-                }else{
-                    return false;
-                }
+    public boolean searchWordInTree(TrieNode t, String word, int i) {
+        char a = word.charAt(i);
+        TrieNode m = t.nexts[a - 'a'];
+        if (m != null) {
+            if (i == word.length() - 1) {
+                ans = true;
+                return m.end;
             }
-            return searchWordInTree(m,word, i+1);
-
+            return searchWordInTree(m, word, i + 1);
         }
         return false;
     }
+
     public boolean search(String word) {
-        char a=word.charAt(0);
-        if(trees[a-'a']==null){
+        char a = word.charAt(0);
+        if (trees[a - 'a'] == null) {
             return false;
-        }else{
-            if(1==word.length()){
-                if(trees[a-'a'].end){
-                    return true;
-                }else{
-                    return false;
-                }
+        } else {
+            if (1 == word.length()) {
+                return trees[a - 'a'].end;
             }
-            return searchWordInTree(trees[a-'a'],word,1);
+            return searchWordInTree(trees[a - 'a'], word, 1);
         }
     }
 
     public boolean startsWith(String prefix) {
-        char a=prefix.charAt(0);
-        ans=false;
-        if(trees[a-'a']==null){
+        char a = prefix.charAt(0);
+        ans = false;
+        if (trees[a - 'a'] == null) {
             return false;
-        }else{
-            if(1==prefix.length()){
+        } else {
+            if (1 == prefix.length()) {
                 return true;
             }
-            searchWordInTree(trees[a-'a'],prefix,1);
+            searchWordInTree(trees[a - 'a'], prefix, 1);
         }
         return ans;
     }
 
-    class TrieNode{
+    static class TrieNode {
         char val;
-        boolean end=false;
-        TrieNode[] nexts=new TrieNode[26];
-        TrieNode(char val){
-            this.val=val;
+        boolean end = false;
+        TrieNode[] nexts = new TrieNode[26];
+
+        TrieNode(char val) {
+            this.val = val;
         }
-        @Override public String toString(){
-            return val+" "+nexts+" "+end;
+
+        @Override
+        public String toString() {
+            return val + " " + Arrays.toString(nexts) + " " + end;
         }
     }
 }
@@ -126,11 +112,3 @@ class TrieNode{
  * boolean param_2 = obj.search(word);
  * boolean param_3 = obj.startsWith(prefix);
  */
-
-/*
- * Your Trie object will be instantiated and called as such:
- * Trie obj = new Trie();
- * obj.insert(word);
- * boolean param_2 = obj.search(word);
- * boolean param_3 = obj.startsWith(prefix);
- */