cpp

Author: Ashish-kumar7

51.cpp

@@ -0,0 +1,87 @@
+class Solution {
+public:
+    bool issafe(vector<vector<int>>&board,int i,int j,int n){
+        //top wala 
+        for(int top=0;top<i;top++){
+            if(board[top][j]==1){
+                return 0;
+            }
+        }
+        
+        //left daigonal
+        
+        int x=i;
+        int y=j;
+        
+        while(x>=0 && y>=0){
+            if(board[x][y]==1){
+                return 0;
+            }
+            x--;
+            y--;
+        }
+        
+        // right daigonal
+        
+         x=i;
+         y=j;
+        
+        while(x>=0 && y<n){
+            if(board[x][y]==1){
+                return 0;
+            }
+            x--;
+            y++;
+        }
+        return 1;
+    }
+
+    bool solve(vector<vector<int>>& board ,int n,int i,vector<vector<string>>&ans){
+        if(i==n){
+            vector<vector<string>> vec( n , vector<string> (n, ".")); 
+            for(int i=0;i<n;i++){
+                for(int j=0;j<n;j++){
+                    if(board[i][j]==1){
+                        vec[i][j]='Q';
+                    }
+                    else{
+                        vec[i][j]='.';
+                    }
+                }
+            }
+            vector<string>temp;
+             for(int i=0;i<n;i++){
+                 string ss="";
+                for(int j=0;j<n;j++){
+                    ss+=vec[i][j];
+                }
+                 temp.push_back(ss);
+            }
+            ans.push_back(temp);
+            return 0;
+        }
+        for(int k=0;k<n;k++){
+            if(issafe(board,i,k,n)){
+                board[i][k]=1;
+                if(solve(board,n,i+1,ans)){
+                    return 1;
+                }
+                board[i][k]=0;   
+            }
+        }  
+        return 0;
+    }
+    
+    vector<vector<string>> solveNQueens(int n) {
+        
+       
+        vector<vector<int>> board( n , vector<int> (n, 0)); 
+        
+        vector<vector<string>>ans;
+        
+        solve(board,n,0,ans);   
+        
+        return ans;
+ 
+    }
+};