602. 俄罗斯套娃信封

class Solution:
    """
    @param: envelopes: a number of envelopes with widths and heights
    @return: the maximum number of envelopes
    """
    ‘‘‘
    大致思路：
    求出最大可能套娃的数量
    ‘‘‘
    def maxEnvelopes(self, envelopes):
        if not envelopes or len(envelopes) == 0:return 0 

        #初始化
        l = len(envelopes)
        dp = [1 for _ in range(l)]

        for i in range(1,l):
            for j in range(i):
                if (envelopes[i] != envelopes[j]):
                    if envelopes[i][0] > envelopes[j][0] and envelopes[i][1] > envelopes[j][1]:
                        dp[i] = max(dp[i],dp[j] + 1)
        
        return max(dp)