Another O(mn) solution


  • 0
    Z

    The idea is to scan each row twice and each column twice.

    class Solution {
        public int maxKilledEnemies(char[][] grid) {
            int m = grid.length, n = (m>0)?grid[0].length : 0;
            int max = 0;
            int [][] count=new int[m][n];
            int countE=0;
            // rows
            for (int i=0; i<m; i++) {
                // row: left to right
                countE=0;
                for (int j=0;j<n;j++){
                    if (grid[i][j]=='W') countE=0;
                    if (grid[i][j]=='E') countE++;
                    if (grid[i][j]=='0') count[i][j]+=countE;
                }
                // row: right to left
                countE=0;
                for (int j=n-1;j>=0;j--){
                    if (grid[i][j]=='W') countE=0;
                    if (grid[i][j]=='E') countE++;
                    if (grid[i][j]=='0') count[i][j]+=countE;
                }
            }
            // cols
            for (int j=0; j<n; j++) {
                // col: top to bottom
                countE=0;
                for (int i=0;i<m;i++){
                    if (grid[i][j]=='W') countE=0;
                    if (grid[i][j]=='E') countE++;
                    if (grid[i][j]=='0') count[i][j]+=countE;
                }
                // col: bottom to top
                countE=0;
                for (int i=m-1;i>=0;i--){
                    if (grid[i][j]=='W') countE=0;
                    if (grid[i][j]=='E') countE++;
                    if (grid[i][j]=='0') {
                        count[i][j]+=countE;
                        max = (count[i][j]>max)?count[i][j]:max;
                    }
                }
            }
            return max;
        }
    }
    

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