МОШ задача C

#include<iostream>
#include<fstream>
#include<vector>
#include<stdint.h>
#include<map>
#include<string>
#include<iomanip>
#include<algorithm>

#define all(container) container.begin(), container.end()
#define fors(counter, start, finish) for (ll counter = start; counter < finish; ++counter)
#define forb(counter, start, finish) for (int counter = start; counter >= finish; --counter)
#define vec(type) std::vector<type>
#define dvec(type) std::vector<std::vector<type>>
#define ll int64_t
//#define fin std::cin

struct versh {
    int idx = 0;
    int weight = 0;
};

int main() {

    std::ifstream fin("input.txt");
    std::ofstream fout("output.txt");

    int m;
    fin >> m;
    fors(i, 0, m) {
        int n, sum = 0; fin >> n;
        vec(versh) v(n);
        fors(i, 0, n) {
            fin >> v[i].weight;
            v[i].idx = i;
            sum += v[i].weight;
        }
        fout << sum / 2 << std::endl;

        std::sort(all(v),
            [](auto& lhs, auto& rhs) {return lhs.weight > rhs.weight; });

        fors(j, 0, n) {
            int k = 0;
            while (v[j].weight != 0 && k < n) {
                if (v[k].weight != 0 && k != j) {
                    v[j].weight--;
                    v[k].weight--;
                    fout << v[j].idx + 1 << " " << v[k].idx + 1 << std::endl;
                }
                k++;
            }
        }
    }

    return 0;

}