Codeforces 500A - New Year Transportation【DFS】

题意：给出n个数，终点t

从第i点能够跳到i+a[i],问能否到达终点

 1 #include<iostream>  

 2 #include<cstdio>  

 3 #include<cstring> 

 4 #include <cmath> 

 5 #include<stack>

 6 #include<vector>

 7 #include<map> 

 8 #include<set>

 9 #include<queue> 

10 #include<algorithm>  

11 #define mod=1e9+7;

12 using namespace std;

13 

14 typedef long long LL;

15 const int INF = 0x7fffffff;

16 const int maxn=50005;

17 int a[maxn],vis[maxn];

18 int n,t;

19 int flag=0;

20 

21 void dfs(int x){

22     if(vis[x]) return;

23     vis[x]=1;

24     int xx=x+a[x];

25     if(xx==t){

26         flag=1;

27         return;

28     }

29     dfs(xx);

30 }

31 

32 int main(){

33     scanf("%d %d",&n,&t);

34     memset(vis,0,sizeof(vis));

35     for(int i=1;i<n;i++) scanf("%d",&a[i]);

36     dfs(1);

37     if(flag) printf("YES\n");

38     else printf("NO\n");

39     return 0;

40 }

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