LeetCode 120. Triangle (Python)最优解--Apolo_Shane

#动态规划皆可用表格解决!
#1\自上往下
class Solution:
    def minimumTotal(self, triangle):
        m = len(triangle)
        l = triangle
        for i in range(1, m):
            for j in range(i + 1):  
                if j == 0:
                    l[i][0] = l[i - 1][0] + l[i][0]
                elif j == i:
                    l[i][i] = l[i - 1][i - 1] + l[i][i]
                else:
                    l[i][j] = min(l[i - 1][j], l[i - 1][j - 1]) + l[i][j]
        return min(l[m - 1][:])
2/自下往上
class Solution:
    def minimumTotal(self, triangle):
        f = [0] * (len(triangle) + 1)
        for row in triangle[::-1]:
            for i in range(len(row)):
                f[i] = row[i] + min(f[i], f[i + 1])
        return f[0]

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