invertGraph.cpp

#include <iostream>
#include <vector>
#include <cstdio>

using namespace std;

int main(){

    int n;
    cin >> n;
    vector<vector<int> > v1;
    vector<vector<int> > v2;

    string s;
    char tmpc;
    int j = 0, tmpi;
    v1.resize(n);
    v2.resize(n);
    scanf("%c", &tmpc);
    while(j < n){
        scanf("%c", &tmpc);
        if (tmpc == ' '){
            cout << 'h';
            continue;
        }
        if (tmpc >= '0' && tmpc <= '9'){
            tmpi = (int)tmpc - 48;
            do{
                scanf("%c", &tmpc);
                if (tmpc != ' ' && tmpc != '\n'){
                    tmpi = tmpi * 10 + ((int)tmpc - 48);
                    // cout << tmpi << endl;
                }
            }while(tmpc != ' ' && tmpc != '\n');
            // cout << "push " << endl;
            v1[j].push_back(tmpi);
        }
        if (tmpc == '\n'){
            j++;
        }
    }

    for (int i = 0; i < n; i++){
        for (int j = 0; j < v1[i].size(); j++)
            v2[v1[i][j] - 1].push_back(i + 1);
    }
    cout << n << endl;
    for (int i = 0; i < n; i++){
        for (int j = 0; j < v2[i].size(); j++)
            cout << v2[i][j] << " ";
        cout << endl;
    }

    return 0;
}