2257. Count Unguarded Cells in the Grid

Leetcode - 2257. Count Unguarded Cells in the Grid

Submission

package dev.namtx.leetcode;  

import java.util.Arrays;  

public class CountUnguardedCellsInTheGrid {  
    static final int GUARD = 2;  
    static final int WALL = -2;  
    static final int UNGUARDED = -1;  
    static final int GUARDED = 1;  

    public int countUnguarded(int m, int n, int[][] guards, int[][] walls) {  
        int[][] mat = new int[m][n];  
        for (int[] row : mat) {  
            Arrays.fill(row, UNGUARDED);  
        }  
        for (int[] wall : walls) {  
            mat[wall[0]][wall[1]] = WALL;  
        }  
        for (int[] guard : guards) {  
            mat[guard[0]][guard[1]] = GUARD;  
        }  
        for (int[] guard : guards) {  
            // top  
            mat[guard[0]][guard[1]] = GUARD;  
            for (int i = guard[0] - 1; i >= 0; i--) {  
                if (mat[i][guard[1]] == WALL || mat[i][guard[1]] == GUARD) break;  
                mat[i][guard[1]] = GUARDED;  
            }  
            // bottom  
            for (int i = guard[0] + 1; i < m; i++) {  
                if (mat[i][guard[1]] == WALL || mat[i][guard[1]] == GUARD) break;  
                mat[i][guard[1]] = GUARDED;  
            }  
            // left  
            for (int i = guard[1] - 1; i >= 0; i--) {  
                if (mat[guard[0]][i] == WALL || mat[guard[0]][i] == GUARD) break;  
                mat[guard[0]][i] = GUARDED;  
            }  
            // right  
            for (int i = guard[1] + 1; i < n; i++) {  
                if (mat[guard[0]][i] == WALL || mat[guard[0]][i] == GUARD) break;  
                mat[guard[0]][i] = GUARDED;  
            }  
        }  

        int ans = 0;  
        for (int i = 0; i < m; i++) {  
            for (int j = 0; j < n; j++) {  
                if (mat[i][j] == UNGUARDED) ans++;  
            }  
        }  

        return ans;  
    }  
}