51nod 1307 绳子与重物（并查集水了一发）

 1 #include<iostream>
 2 #include<algorithm>
 3 #include<cstring>
 4 #include<cstdio>
 5 #include<sstream>
 6 #include<vector>
 7 #include<stack>
 8 #include<queue>
 9 #include<cmath>
10 #include<map>
11 #include<set>
12 using namespace std;
13 typedef long long ll;
14 const int INF = 0x3f3f3f3f;
15 const int maxn=50000+5;
16 const int mod=1e9+7;
17 
18 int n;
19 int p[maxn];
20 int c[maxn],w[maxn],f[maxn];
21 
22 int main()
23 {
24     //freopen("in.txt","r",stdin);
25     while(~scanf("%d",&n))
26     {
27         for(int i=0;i<n;i++)  p[i]=i;
28         int ans=n;
29         for(int i=0;i<n;i++)
30         {
31             scanf("%d%d%d",&c[i],&w[i],&f[i]);
32             if(ans!=n)   continue;
33             if(f[i]==-1)  continue;
34             p[i]=f[i];
35             int x=i;
36             while(true)
37             {
38                 x=p[x];
39                 w[x]+=w[i];
40                 if(w[x]>c[x])  {ans=i;break;}
41                 if(x==p[x])  break;
42             }
43         }
44         printf("%d\n",ans);
45     }
46     return 0;
47 }