袋鼠过河
dp用来保存跳了多少步
#include<iostream>
#include<algorithm>
#include<cstring>
using namespace std;
#define FOR(I,N) for(int i=0;i<n;++i)
#define min(x,y) (x<y?x:y)
const int maxn = 1e4+5;
#define INF 1<<30
int arr[maxn];
int dp[maxn];
int main()
{
int n,flag;
while(cin>>n)
{
FOR(I,N) cin>>arr[i];
for(int i=0;i<=n;++i)
{
dp[i]=INF;
}
dp[0]=1;
flag=1;
FOR(I,N)
{
if(dp[i]==INF)
{
flag=0;
break;
}
for(int j=i+1;j<=i+arr[i];++j)
{
dp[j]=min(dp[i]+1,dp[j]);
/*
cout<<i<<endl;
FOR(I,N)
{
cout<<dp[i]<<" ";
}
cout<<endl;
*/
}
}
if(flag) cout<<dp[n]-1<<endl;
else cout<<"-1"<<endl;
}
return 0;
}