Create Count Submatrices With Equal Frequency of X and Y.cpp

Author: Ayushluthra2001

Count Submatrices With Equal Frequency of X and Y.cpp

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+class Solution {
+public:
+    int numberOfSubmatrices(vector<vector<char>>& grid) {
+        int r = grid.size();
+        int c = grid[0].size();
+        vector<vector<int>> prex(r+1, vector<int>(c+1, 0));
+        vector<vector<int>> prey(r+1, vector<int>(c+1, 0));
+
+        for(int i = 1 ; i <= r ; i++){
+            for(int j = 1 ; j <= c ; j++){
+                prex[i][j] = prex[i-1][j] + prex[i][j-1] - prex[i-1][j-1] + (grid[i-1][j-1]=='X' ? 1 : 0);
+                prey[i][j] = prey[i-1][j] + prey[i][j-1] - prey[i-1][j-1] + (grid[i-1][j-1]=='Y' ? 1 : 0);
+            }
+        }
+        int res = 0;
+        for(int i = 0 ; i < r ; i++){
+            for(int j = 0 ; j < c ; j++){
+                int cx = prex[i+1][j+1] - prex[0][j+1] - prex[i+1][0] + prex[0][0];
+                int cy = prey[i+1][j+1] - prey[0][j+1] - prey[i+1][0] + prey[0][0];
+                if(cx == cy and cx > 0){
+                    res++;
+                }
+            }
+        }
+        return res;
+    }
+};