huangzimai 2016-10-15 22:27:37
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#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <string>
#include <cstring>
#include <cmath>
#include <algorithm>
using namespace std;
int g[205][205];
int main()
{
int a,b,n,k;
cin>>n>>a>>b;
for (int i=1;i<=n;i++)
for (int j=1;j<=n;j++)
g[i][j]=9999;
for (int i=1;i<=n;i++)
{
g[i][i]=0;
cin>>k;
if (i+k<=n) g[i][i+k]=1;
if (i-k>0) g[i][i-k]=1;
}
for (int k=1;k<=n;k++)
for (int i=1;i<=n;i++) if (i!=k)
for (int j=1;j<=n;j++) if ((i!=j)&&(j!=k))
if (g[i][j]>g[i][k]+g[k][j])
g[i][j]=g[i][k]+g[k][j];
if (g[a][b]==9999) cout<<"-1"<<endl;
else cout<<g[a][b]<<endl;
}