Solucion al problema A del Good Bye 2014

Solucionp2.cpp

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <string>
#include <vector>
#include <cmath>
#include <queue>
#include <set>
#include <map>
using namespace std;
#define dprint(v) cout << #v"=" << v << endl
#define forr(i, a, b) for(int i=(a); i<(b); i++)
#define forn(i, n) forr(i, 0, n)
#define dforn(i, n) for(int i=(n)-1; i>=0; i--)
#define forall(it,v) for(typeof((v).begin()) it=(v).begin();it!=(v).end();++it)
#define sz(c) ((int)c.size())
#define zero(v) memset(v, 0, sizeof(v))
typedef long long ll;
#define ii pair<int, int>
#define mkp make_pair
#define fst first
#define snd second
#define pb push_back



ll t,r,b,n,m,k,rt;
string s;
int a[100000];

int main()
{
#ifndef ONLINE_JUDGE
    //~ freopen("a.in", "r", stdin);
#endif
    while (cin >> n >> k){
        rt = 0;
        forn (i,n-1)
            cin >> a[i];
        a[n-1] = 2;
        int j = 0;
        while (j <= n-1){
            if (j == k-1)
                rt = 1;
            j+= a[j];           
        }
        if (rt)
            cout << "YES";
        else
            cout << "NO";

    }
        
    return 0;
}