CCC '07 S4 - Waterpark

#include <iostream>
#include <stdio.h>
#include <vector>
#include <queue>
#include <cstring>

using namespace std;

/***
7
1 2
2 3
1 3
2 4
1 4
2 6
4 6
2 5
7 5
6 7
0 0
***/

int main(){
    int n;
    int i, j;
    scanf(" %d", &n);
    int w[n];
    memset(w, 0, sizeof(w));
    w[0] = 1;

    vector <int> v[n];

    while(1){
        scanf(" %d %d", &i, &j);
        if(i==0){
            break;
        }
        i--;
        j--;
        v[min(i, j)].push_back(max(i, j));
    }

    for(i=0; i<n; i++){
        if(w[i] == 0) continue;
        for(j=0; j<v[i].size(); j++){
            w[v[i][j]] += w[i];
        }
    }
    printf("%d", w[n-1]);

}