poj 1949 Chores 最长路

题目链接

求出最长路.....

 #include <iostream>
 #include <vector>
 #include <cstdio>
 #include <cstring>
 #include <algorithm>
 #include <cmath>
 #include <map>
 #include <set>
 #include <string>
 #include <queue>
 using namespace std;
 #define pb(x) push_back(x)
 #define ll long long
 #define mk(x, y) make_pair(x, y)
 #define lson l, m, rt<<1
 #define mem(a) memset(a, 0, sizeof(a))
 #define rson m+1, r, rt<<1|1
 #define mem1(a) memset(a, -1, sizeof(a))
 #define mem2(a) memset(a, 0x3f, sizeof(a))
 #define rep(i, a, n) for(int i = a; i<n; i++)
 #define ull unsigned long long
 typedef pair<int, int> pll;
 const double PI = acos(-1.0);
 const double eps = 1e-;
 const int mod = 1e9+;
 const int inf = ;
 const int dir[][] = { {-, }, {, }, {, -}, {, } };
 const int maxn = 1e6+;
 int head[maxn], dis[], num, val[];
 struct node
 {
     int to, nextt, c;
 }e[maxn];
 void add(int u, int v, int c) {
     e[num].to = v;
     e[num].nextt = head[u];
     e[num].c = c;
     head[u] = num++;
 }
 void init() {
     mem1(dis);
     mem1(head);
     num = ;
 }
 int dfs(int u) {
     if(~dis[u])
         return dis[u];
     int ret = val[u], ans = ;
     for(int i = head[u]; ~i; i = e[i].nextt) {
         int v = e[i].to;
         ans = max(ans, dfs(v));
     }
     return dis[u] = ans+ret;
 }
 int main()
 {
     int n, x, y;
     while(cin>>n) {
         init();
         for(int i = ; i<=n; i++) {
             scanf("%d", &val[i]);
             scanf("%d", &x);
             while(x--) {
                scanf("%d", &y);
                add(y, i, val[i]);
             }
         }
         for(int i = ; i<=n; i++) {
             if(dis[i]==-) {
                 dis[i] = dfs(i);
             }
         }
         int ans = ;
         for(int i = ; i<=n; i++) {
             ans = max(ans, dis[i]);
         }
         printf("%d\n", ans);
     }
     return ;
 }