Leetcode#64||Minimum Path Sum

public class Solution {
    public int minPathSum(int[][] grid) {
        if (grid == null || grid.length == 0 || grid[0].length == 0) {
            return -1;
        }
        
        int m = grid.length;
        int n = grid[0].length;
        
        int[] paths = new int[n];
        
        paths[0] = grid[0][0];
        for (int j = 1; j < n; j++) {
            paths[j] = paths[j - 1] + grid[0][j];
        }
        
        for (int i = 1; i < m; i++) {
            paths[0] += grid[i][0];
            
            for (int j = 1; j < n; j++) {
                paths[j] = Math.min(paths[j - 1], paths[j]) + grid[i][j];
            }
        }
        
        return paths[n - 1];
    }
}