sicily 1035. DNA matching

#include<iostream>
#include<cstdio>
#include<string>
#include<algorithm>
using namespace std;

bool cmp(string a, string b);
bool match(string a, string b);


int main(void) {
    int testSize, couple;
    string str[101];
    int len[101];
    bool used[101];

    // for each test case: (t<=20)
    cin >> testSize;
    while(testSize--) {
        // scan and store n strings(n <= 100)
        cin >> couple;
        for (int i = 0; i < couple; ++i) {
            cin >> str[i];
        }

        // sort by length
        sort(str, str + couple, cmp);
        //sort(<#_RandomAccessIterator __first#>, <#_RandomAccessIterator __last#>, <#_Compare __comp#>)

        for (int i = 0; i < couple; ++i) {
            // store length
            len[i] = str[i].size();
            // init used
            used[i] = false;
        }

        int count = 0;

        for (int i = 0; i < couple; ++i) {
            if (!used[i]) {
                for (int j = i + 1; j < couple && len[j] == len[i]; ++j) {
                    if (match(str[i], str[j]) && !used[j]) {
                        count++;
                        used[i] = used[j] = true;
                        break;
                    }
                }
            }
        }

        cout << count << '
';
    }

    return 0;
}

bool cmp(string a,string b)
{
    return a.size() > b.size();
}
bool match(string a,string b){
    int len = a.size();
    for (int i = 0; i<len; i++) {
        if (a[i] == 'A' && b[i] != 'T')
            return false;
        if (a[i] == 'T' && b[i] != 'A')
            return false;
        if (a[i] == 'C' && b[i] != 'G')
            return false;
        if (a[i] == 'G' && b[i] != 'C')
            return false;
    }
    return true;
}