Google Kick Start 2020 Round B - Bike Tour

LINK

Problem

Li has planned a bike tour through the mountains of Switzerland. His tour consists of N checkpoints, numbered from 1 to N in the order he will visit them. The i-th checkpoint has a height of Hi.

A checkpoint is a peak if: It is not the 1st checkpoint or the N-th checkpoint, and The height of the checkpoint is strictly greater than the checkpoint immediately before it and the checkpoint immediately after it.

Please help Li find out the number of peaks.

Example

input1: 
4
3
10 20 14
4
7 7 7 7
5
10 90 20 90 10
3
10 3 10

output1:
Case #1: 1
Case #2: 0
Case #3: 2
Case #4: 0

Solution

As scanning through the list, keep track of three values: first, sec, third. Check if any satisfies the conditions for being a peak.

int biketour(){
    int tests, size;
    cin >> tests;
    for(size_t j = 0; j < tests; ++j){
        cin >> size;
        int bfr, cur, after, count = 0;
        cin >> bfr;
        cin >> cur;
        for(size_t i = 0; i < size-2; ++i){
            cin >> after;
            if(bfr < cur && cur > after){
                    ++count;
            }
            bfr = cur;
            cur = after;
        }
        
        cout << "Case #" << j+1 << ": " << count << endl;
    }
    return 0;
}

Time copmlexity: O(t*n)