Word Search 2,Backtracking+Tries Question (#921)

* bt added

* mergeSort

Author: m-kathyayani125

C++/Backtracking/bt.cpp

@@ -0,0 +1,66 @@
+#include<bits/stdc++.h>
+using namespace std;
+class TrieNode{
+public:
+    bool is_end;
+    vector<TrieNode*> children;
+    TrieNode(){
+        is_end=false;
+        children=vector<TrieNode*>(26, NULL);
+    }   
+};
+
+class Trie{
+public:
+    TrieNode* getRoot(){return root;}
+    Trie(vector<string>& words){
+        root=new TrieNode();
+        for(int i=0; i<words.size(); ++i)
+            addWord(words[i]);
+    }
+    void addWord(const string& word){
+        TrieNode* cur=root;
+        for(int i=0; i<word.size(); ++i){
+            int index=word[i]-'a';
+            if(cur->children[index]==NULL)   
+               cur->children[index]=new TrieNode();
+            cur=cur->children[index];    
+        }
+        cur->is_end=true;
+    }
+private:
+    TrieNode* root;
+};
+
+class Solution {
+public:
+    vector<string> findWords(vector<vector<char>>& board, vector<string>& words) {
+        Trie* trie = new Trie(words);
+        TrieNode* root=trie->getRoot();
+        set<string> result_set;
+        for(int x=0; x<board.size(); ++x)
+            for(int y=0; y<board[0].size(); ++y)
+                findWords(board, x, y, root, "", result_set);
+        
+        vector<string> result;
+        for(auto it:result_set)    result.push_back(it);
+        return result;        
+    }
+private:
+    void findWords(vector<vector<char>>& board, int x, int y, TrieNode* root, string word, set<string>& result){
+        if(x<0||x>=board.size()||y<0||y>=board[0].size() || board[x][y]==' ') return;
+        
+        if(root->children[board[x][y]-'a'] != NULL){
+            word=word+board[x][y];
+            root=root->children[board[x][y]-'a']; 
+            if(root->is_end) result.insert(word);
+            char c=board[x][y];
+            board[x][y]=' ';
+            findWords(board, x+1, y, root, word, result);
+            findWords(board, x-1, y, root, word, result);
+            findWords(board, x, y+1, root, word, result);
+            findWords(board, x, y-1, root, word, result);
+            board[x][y]=c;        
+        }
+    }
+};

Java/Algorithm/SortingAlgorithm/Mergesort_recursive.java

@@ -0,0 +1,68 @@
+import java.util.Scanner;
+public class Mergesort_recursive
+{
+    public static void main(String a[])
+    {
+        int temp;
+        Scanner sc = new Scanner(System.in);
+        System.out.println("Enter array size");
+        int n = sc.nextInt();
+        int[] list = new int[n];
+        System.out.println("Enter numbers ");
+        for (int i = 0; i < n; i++)
+        {
+            int number = sc.nextInt();
+            list[i] = number;
+        }
+        System.out.println("List before sorting \n");
+        for (int i = 0; i < list.length; i++)
+            System.out.print(list[i] + " ");
+        System.out.println();
+
+        mergeSort(list, 0, list.length - 1);
+        System.out.print("List after sorting \n");
+        for (int i = 0; i < list.length; i++)
+            System.out.print(list[i] + " ");
+        System.out.println();
+    }
+
+    public static void mergeSort(int list[], int low, int high)
+    {
+        if (low >= high)
+        {
+            return;
+        }
+        int middle = (low + high) / 2;
+        mergeSort(list, low, middle);
+        mergeSort(list, middle + 1, high);
+        merge(list, low, middle, high);
+    }
+    private static void merge(int list[], int low, int middle, int high)
+    {
+        int IstList_end = middle;
+        int IIndList_start = middle + 1;
+        int l = low;
+        while ((l <= IstList_end) && (IIndList_start <= high))
+        {
+            if (list[low] < list[IIndList_start])
+            {
+
+                low++;
+            }
+            else
+            {
+                int temp = list[IIndList_start];
+
+                for (int j = IIndList_start - 1; j >= low; j--)
+                {
+
+                    list[j + 1] = list[j];
+                }
+                list[low] = temp;
+                low++;
+                IstList_end++;
+                IIndList_start++;
+            }
+        }
+    }
+}