Solution as on 21-03-2022 10:04 pm

Author: knockcat

0036. Valid Sudoku.cpp

@@ -0,0 +1,43 @@
+// 36.✅ Valid Sudoku
+
+class Solution
+{
+public:
+    bool isValid(vector<vector<char>> &board, int row, int col)
+    {
+        int c = board[row][col];
+        board[row][col] = '.';
+        for (int i = 0; i < 9; i++)
+            if (board[row][i] == c)
+                return false;
+        for (int i = 0; i < 9; i++)
+            if (board[i][col] == c)
+                return false;
+        for (int i = 0; i < 3; i++)
+            for (int j = 0; j < 3; j++)
+                if (board[row / 3 * 3 + i][col / 3 * 3 + j] == c)
+                    return false;
+
+        board[row][col] = c;
+        return true;
+    }
+
+    bool isValidSudoku(vector<vector<char>> &board)
+    {
+
+        // Go for all the rows & columns looking for an invalid number
+        // If you find an invalid entry, return false
+        // If you don not find an invalid entry till the end, it has to be good, return true.
+        for (int i = 0; i < 9; i++)
+        {
+            for (int j = 0; j < 9; j++)
+            {
+                if (board[i][j] != '.' && !isValid(board, i, j))
+                {
+                    return false;
+                }
+            }
+        }
+        return true;
+    }
+};