Question
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
with (time[i] + time[j]) % 60 == 0
.
Example 1:
Input: [30,20,150,100,40] Output: 3 Explanation: Three pairs have a total duration divisible by 60: (time[0] = 30, time[2] = 150): total duration 180 (time[1] = 20, time[3] = 100): total duration 120 (time[1] = 20, time[4] = 40): total duration 60
Example 2:
Input: [60,60,60] Output: 3 Explanation: All three pairs have a total duration of 120, which is divisible by 60.
Note:
1 <= time.length <= 60000
1 <= time[i] <= 500
Difficulty:Medium
Category:
Analyze
Solution
class Solution {
public:
int numPairsDivisibleBy60(vector<int>& time) {
int ans = 0;
vector<int> vec(61, 0);
for (int t : time) {
t %= 60;
if (t == 0) ans += vec[0];
else ans += vec[60-t];
vec[t]++;
}
return ans;
}
};