题目

法1：二维DP

必须掌握！

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

        return matrix[m - 1][n - 1];
    }
}