LeetCode 542. 01 Matrix

class Solution {
public:
    vector<vector<int>> updateMatrix(vector<vector<int>>& matrix) {
        int rows = matrix.size();
        if (rows == 0) 
            return matrix;
        int cols = matrix[0].size();
        vector<vector<int>> dist(rows, vector<int> (cols, INT_MAX - 100000));

        //First pass: check for left and top
        for (int i = 0; i < rows; i++) {
            for (int j = 0; j < cols; j++) {
                if (matrix[i][j] == 0) {
                    dist[i][j] = 0;
                } else {
                    if (i > 0)
                        dist[i][j] = min(dist[i][j], dist[i - 1][j] + 1);
                    if (j > 0)
                        dist[i][j] = min(dist[i][j], dist[i][j - 1] + 1);
                }
            }
        }

        //Second pass: check for bottom and right
        for (int i = rows - 1; i >= 0; i--) {
            for (int j = cols - 1; j >= 0; j--) {
                if (i < rows - 1)
                    dist[i][j] = min(dist[i][j], dist[i + 1][j] + 1);
                if (j < cols - 1)
                    dist[i][j] = min(dist[i][j], dist[i][j + 1] + 1);
            }
        }
        return dist;
    }
};