[leetcode] Minimum Path Sum

Given a m x n grid filled with non-negative numbers, find a path from top left to bottom right which minimizes the sum of all numbers along its path.

Note: You can only move either down or right at any point in time.

思路很簡單，DP，f[i][j] = min(f[i][j-1], f[i-1][j]) + grid[i][j] 

class Solution:
    # @param grid, a list of lists of integers
    # @return an integer
    def minPathSum(self, grid):
        m = len(grid)
        n = len(grid[0])
        f = [[0 for col in range(n)] for row in range(m)]
        f[0][0] = grid[0][0]
        for i in range(1,n):
            f[0][i] = f[0][i - 1] + grid[0][i]
        for i in range(1,m):
            f[i][0] = f[i - 1][0] + grid[i][0]
        for i in range(1,m):
            for j in range(1,n):
                f[i][j] = min(f[i][j-1], f[i-1][j]) + grid[i][j]
        return f[m-1][n-1]