Revise paste Untitled

#include <iostream>
#include <vector>
#include <queue>
#include <algorithm>
#include <set>
#include <cstring>
using namespace std;

using namespace std;
vector<int>graph[2000];
int idx[2000];
struct node{
int a;
int b;
int distance;
node(int _a, int _b, int _distance){
    a = _a;
    b = _b;
    distance = _distance;
}
bool operator < (const node &tmp)const{
return distance < tmp.distance;
}
};

int find_root(int a){
while(idx[a]!=a){
    idx[a]=idx[idx[a]];
    a=idx[a];
}
return a;
}

bool check(int a, int b){
if(find_root(a)!=find_root(b)){
    return false;
}
else{
    return true;
}
}

void unite_two_elements(int a, int b){
int _a=find_root(a);
int _b=find_root(b);
if(check(a, b)==false){
idx[_a]=_b;
}
}

int main()
{
    for(int i=0; i<2000; i++){
    idx[i]=i;
    }
    int n;
    cin>>n;
    vector<node>v;

for(int i=0; i<n; i++){
        for(int j=i+1; j<n; j++){
            int a;
            cin>>a;
            v.push_back(node(i, j, a));
        }
    }

sort(v.begin(), v.end());
    for(int i=0; i<v.size(); i++){
    int a=v[i].a;
    int b=v[i].b;
    int d=v[i].distance;
    if(check(a, b)==false){
        unite_two_elements(a, b);
        graph[a].push_back(b);
        graph[b].push_back(a);
    }
    }
    for(int i=0; i<n; i++){
        cout<<(int) graph[i].size() << " ";
        sort(graph[i].begin(),   graph[i].end());
        for(int j=0; j<graph[i].size(); j++){
            cout<<graph[i][j] + 1<< " ";
        }
        cout<<endl;
    }
    return 0;
}