1010. Pairs of Songs With Total Durations Divisible by 60

In a list of songs, the i-th song has a duration of time[i] seconds. 

Return the number of pairs of songs for which their total duration in seconds is divisible by 60.  Formally, we want the number of indices i, j such that i < j with (time[i] + time[j]) % 60 == 0.

这个是模的two sum问题

class Solution(object):
    def numPairsDivisibleBy60(self, time):
        """
        :type time: List[int]
        :rtype: int
        """
        d = {}
        ans = 0
        for value in time:
            if (60 - (value % 60)) % 60 in d:
                ans += d[(60 - (value % 60)) % 60]
            if (value % 60) in d:
                d[value % 60] += 1
            else:
                d[value % 60] = 1
        return ans