120 Triangle

题目： 120 Triangle

这道题纯dp, 但是有一个比一下代码优化的做法，就是从底部bottomu-up dp.

class Solution:
    # @param triangle, a list of lists of integers
    # @return an integer
    def minimumTotal(self, triangle):
        n = len(triangle)
        ans = [[0] * n for i in range(0,n)]
        if n == 0:
            return 0
        ans[0][0] = triangle[0][0]
        for i in range(1, n):
            ans[i][0] = ans[i-1][0] + triangle[i][0]
            ans[i][i] = ans[i-1][i-1] + triangle[i][i]
            for j in range(1,i):
                ans[i][j] = min(ans[i-1][j-1], ans[i-1][j]) + triangle[i][j]
        return min(ans[-1])