MinimumPathSum.java

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