Added Solution - GfG to GitHub

Author: DLSireesha

Difficulty: Hard/Solve the Sudoku/solve-the-sudoku.cpp

@@ -0,0 +1,99 @@
+//{ Driver Code Starts
+#include <bits/stdc++.h>
+using namespace std;
+
+
+// } Driver Code Ends
+
+
+class Solution {
+  public:
+    // Function to find a solved Sudoku.
+    bool solve(int i, int j, vector<vector<int>>& board, vector<vector<bool>> &row, vector<vector<bool>> &col, vector<vector<bool>> &sub_box){
+        if(i==9) return true;
+        if(j==9) return solve(i+1, 0, board, row, col, sub_box);
+        if(board[i][j]!=0)return solve(i, j+1, board, row, col, sub_box);
+                
+        for(int num=1; num<=9; num++){
+            int box_no = (i/3)*3+(j/3);
+                    
+            if(row[i][num]==0 && col[j][num]==0 && sub_box[box_no][num]==0){
+                row[i][num] = 1;
+                col[j][num] = 1;
+                sub_box[box_no][num] = 1;
+                board[i][j] = num;
+    
+                if(solve(i, j+1, board, row, col, sub_box)) return true;
+    
+                row[i][num] = 0;
+                col[j][num] = 0;
+                sub_box[box_no][num] = 0;
+                board[i][j] = 0;
+            }
+        }
+    
+        return false;
+    }
+    
+    bool solveSudoku(vector<vector<int>>& board) {
+        vector<vector<bool>> sub_box(9, vector<bool> (9+1, false));
+        vector<vector<bool>> col(9, vector<bool> (9+1, false));
+        vector<vector<bool>> row(9, vector<bool> (9+1, false));
+            
+        for(int i=0; i<9; i++)
+            for(int j=0; j<9; j++)
+                if(board[i][j]!=0){
+                    int num = board[i][j];
+                    int box_no = (i/3)*3 + j/3;
+                        
+                    row[i][num] = 1;
+                    col[j][num] = 1;
+                    sub_box[box_no][num] = 1;
+                }
+                
+        if(solve(0, 0, board, row, col, sub_box)) return true;
+        return false;
+    }
+};
+
+//{ Driver Code Starts.
+
+vector<int> inputLine() {
+    string str;
+    getline(cin, str);
+    stringstream ss(str);
+    int num;
+    vector<int> res;
+    while (ss >> num) {
+        res.push_back(num);
+    }
+    return res;
+}
+
+int main() {
+    int t;
+    cin >> t;
+    cin.ignore();
+    while (t--) {
+        vector<vector<int>> grid;
+        for (int i = 0; i < 9; i++) {
+            vector<int> v = inputLine();
+            grid.push_back(v);
+        }
+
+        Solution ob;
+
+        ob.solveSudoku(grid);
+
+        for (auto v : grid) {
+            for (auto elem : v) {
+                cout << elem << " ";
+            }
+            cout << endl;
+        }
+
+        cout << "~" << endl;
+    }
+    return 0;
+}
+// } Driver Code Ends