Create 840. Magic Squares In Grid (#551)

Author: Chayandas07

840. Magic Squares In Grid

@@ -0,0 +1,43 @@
+class Solution {
+private:
+    bool is9Digits(vector<vector<int>> &grid,int i,int j,int n,int m){
+        int sum1=0,sum2=0,sum3=0;
+        int sum4=0,sum5=0,sum6=0;
+
+        for(int k=0; k<3; k++){
+            sum1 += grid[i][j+k];
+            sum2 += grid[i+1][j+k];
+            sum3 += grid[i+1][j+k];
+
+            sum4 += grid[i+k][j];
+            sum5 += grid[i+k][j+1];
+            sum6 += grid[i+k][j+2];
+        }
+
+        if(sum1 != sum2 || sum1 != sum3 || sum1 != sum4 
+            || sum4 != sum5 || sum4 != sum6) return false;
+
+        set<int> st;
+        for(int ii=i; ii<=i+2; ii++){
+            for(int jj=j; jj<=j+2; jj++){
+                if(grid[ii][jj] > 9 || grid[ii][jj] < 1) return false;
+                st.insert(grid[ii][jj]);
+            }
+        }
+        return st.size() == 9;
+    } 
+public:
+    int numMagicSquaresInside(vector<vector<int>>& grid) {
+        int n = grid.size(),m = grid[0].size();
+        int ans = 0;
+
+        for(int i=0; i<n-2; i++){
+            for(int j=0; j<n-2; j++){
+                if(is9Digits(grid,i,j,n,m)){
+                    ans++;
+                }
+            }
+        }
+        return ans;
+    }
+};