FAANG | OA Coding Questions and Solutions | Set - 4 | 2022

Question

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Here is the link : https://www.desiqna.in/tag/amazon_oa

Answer 1

You are given a list of songs where the ith 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.

 

Example 1:

Input: time = [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: time = [60,60,60]
Output: 3
Explanation: All three pairs have a total duration of 120, which is divisible by 60.

 

Constraints:

• 1 <= time.length <= 6 * 104
• 1 <= time[i] <= 500

Code : 

    int numPairsDivisibleBy60(vector<int>& time) {
        vector<int> c(60);
        int res = 0;
        for (int t : time) {
            res += c[(600 - t) % 60];
            c[t % 60] += 1;
        }
        return res;
    }