1010. Pairs of Songs With Total Durations Divisible by 60

class Solution:
    def numPairsDivisibleBy60(self, time: List[int]) -> int:
        d = [0]*60
        res = 0
        for t in time:
            rem = t%60
            res += d[(60-rem%60)%60] # rem =0  
            d[rem] += 1
        return res 

class Solution:
    def numPairsDivisibleBy60(self, time: List[int]) -> int:
        d = [0]*60
        for t in time:
            rem = t%60
            d[rem] += 1 
        res = 0
        for i in range(60):
            if d[i] == 0: continue
            if i == 0 or i == 30: 
                res += d[i]*(d[i]-1)
            else:
                res += d[i]*d[60-i]
        return res//2