1 #include <iostream>
 2 #include <stdio.h>
 3 using namespace std;
 4
 5 const int MAXN = 5e4 + 10;
 6 struct node{
 7     int c, w, pre;
 8 }gel[MAXN];
 9 int num[MAXN];//num[i]为编号为i的绳子当前可以承受的最大重量
10
11 int main(void){
12     int n, ans = -1;
13     scanf("%d", &n);
14     for(int i = 0; i < n; i++){
15         scanf("%d%d%d", &gel[i].c, &gel[i].w, &gel[i].pre);
16         if(ans != -1) continue;
17         num[i] = gel[i].c;
18         int cnt = i;
19         while(cnt != -1){
20             num[cnt] -= gel[i].w;
21             if(ans == -1 && num[cnt] <= -1) ans = i;
22             cnt = gel[cnt].pre;//指向cnt的父亲节点
23         }
24     }
25     if(ans == -1) cout << n << endl;
26     else cout << ans << endl;
27     return 0;
28 }

 1 #include <iostream>
 2 #include <stdio.h>
 3 #include <vector>
 4 #define ll long long
 5 using namespace std;
 6
 7 const int MAXN = 5e4 + 10;
 8 struct node{
 9     int c, w, pre;
10 }gel[MAXN];
11 vector<int> sol[MAXN];
12 bool flag;
13
14 ll dfs(int u, int x){
15     ll sum = gel[u].w;
16     if(u > x) return 0;//mid边后面的不要算上去
17     for(int i = 0; i < sol[u].size(); i++){
18         sum += dfs(sol[u][i], x);
19     }
20     if(sum > gel[u].c && u) flag = false;//0是一个虚根,并没有对应的边
21     return sum;
22 }
23
24 int main(void){
25     int n;
26     scanf("%d", &n);
27     for(int i = 1; i <= n; i++){
28         scanf("%d%d%d", &gel[i].c, &gel[i].w, &gel[i].pre);
29         gel[i].pre++;
30         sol[gel[i].pre].push_back(i);
31     }
32     int l = 1, r = n, cnt = n;
33     while(l <= r){
34         flag = true;
35         int mid = (l + r) >> 1;
36         dfs(0, mid);
37         if(flag) cnt = mid, l = mid + 1;
38         else r = mid - 1;
39     }
40     printf("%d\n", cnt);
41 }

 1 #include <iostream>
 2 #include <stdio.h>
 3 #include <vector>
 4 #define ll long long
 5 using namespace std;
 6
 7 const int MAXN = 1e5 + 10;
 8 struct node{
 9     ll c, w, p;
10 }gel[MAXN];
11
12 ll ww[MAXN];
13 vector<int> vt[MAXN];
14 int pre[MAXN], sol;
15
16 int find(int x){
17     return pre[x] == x ? x : pre[x] = find(pre[x]);
18 }
19
20 void update(int u){
21     for(int i = 0; i < vt[u].size(); i++){
22         gel[u].w += gel[vt[u][i]].w;
23         pre[vt[u][i]] = u;
24     }
25     while(gel[u].w > gel[u].c){//u即为当前根节点
26         gel[find(sol)].w -= ww[sol];
27         sol--;
28     }
29 }
30
31 int main(void){
32     int n;
33     scanf("%d", &n);
34     for(int i = 1; i <= n; i++){
35         scanf("%lld%lld%lld", &gel[i].c, &gel[i].w, &gel[i].p);
36         gel[i].p++;
37         vt[gel[i].p].push_back(i);
38         ww[i] = gel[i].w;//后面会对gel操作,所以需要先记录下gel的初始值来
39         pre[i] = i;
40     }
41     sol = n;
42     for(int i = n; i > 0; i--){
43         update(i);
44     }
45     printf("%d\n", sol);
46     return 0;
47 }