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hdu 4276 The Ghost Blows Light(DP-树形DP)

2024-07-20 05:52:41   214人阅读

The Ghost Blows Light

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 2240    Accepted Submission(s): 688


Problem Description

My name is Hu Bayi, robing an ancient tomb in Tibet. The tomb consists of N rooms (numbered from 1 to N) which are connected by some roads (pass each road should cost some time). There is exactly one route between any two rooms, and each room contains some treasures. Now I am located at the 1st room and the exit is located at the Nth room. 
Suddenly, alert occurred! The tomb will topple down in T minutes, and I should reach exit room in T minutes. Human beings die in pursuit of wealth, and birds die in pursuit of food! Although it is life-threatening time, I also want to get treasure out as much as possible. Now I wonder the maximum number of treasures I can take out in T minutes.
 

Input
There are multiple test cases.
The first line contains two integer N and T. (1 <= n <= 100, 0 <= T <= 500)
Each of the next N - 1 lines contains three integers a, b, and t indicating there is a road between a and b which costs t minutes. (1<=a<=n, 1<=b<=n, a!=b, 0 <= t <= 100)
The last line contains N integers, which Ai indicating the number of treasure in the ith room. (0 <= Ai <= 100)
 

Output
For each test case, output an integer indicating the maximum number of treasures I can take out in T minutes; if I cannot get out of the tomb, please output "Human beings die in pursuit of wealth, and birds die in pursuit of food!".
 

Sample Input
5 101 2 2 2 3 22 5 33 4 31 2 3 4 5
 

Sample Output
11
 


 

 

 

 

 

 

 

 

#include <iostream>#include <cstdio>#include <vector>#include <cstring>#include <algorithm>using namespace std;const int maxn = 110;const int maxt = 510;int dp[maxn][maxt] , A[maxn] , vis[maxn] , ans[maxt];int way[maxn];int N , T , cnt , sumT , route;struct edge{    int u , v , t , next;    edge(int a = 0 , int b = 0, int c = 0 , int d = 0){        u = a , v = b , t = c , next = d;    }}e[4*maxn];int head[maxn];void add(int u , int v , int t){    e[cnt] = edge(u , v , t , head[u]);    head[u] = cnt++;}void initial(){    for(int i = 0; i < maxn; i++){        head[i] = -1;        A[i] = 0;        vis[i] = 0;        for(int j = 0; j < maxt; j++) dp[i][j] = 0;    }    for(int i = 0; i < maxt; i++) ans[i] = 0;    cnt = 0;    sumT = 0;    route = 0;}void readcase(){    int u , v , t;    for(int i = 0; i < N-1; i++){        scanf("%d%d%d" , &u , &v , &t);        add(u , v , t);        add(v , u , t);    }    for(int i = 1; i <= N; i++){        scanf("%d" , &A[i]);    }}void DP(int k , int f){    dp[k][0] = A[k];    for(int i = head[k]; i != -1; i = e[i].next){        int son = e[i].v;        if(son != f){            DP(son , k);            if(vis[son]) continue;            for(int t = T; t >= 0; t--){                if(dp[k][t] == 0 && t != 0) continue;                for(int j = T; j >= 0; j--){                    if(dp[son][j] != 0 && t+j+2*e[i].t <= T && dp[k][t+j+2*e[i].t] < dp[k][t]+dp[son][j]) dp[k][t+j+2*e[i].t] = dp[k][t]+dp[son][j];                }            }        }    }}bool dfs(int k , int index , int f){    way[index] = k;    route = index;    if(k == N) return true;    for(int i = head[k]; i != -1; i = e[i].next){        int son = e[i].v;        if(f != son){            sumT += e[i].t;            if(dfs(son , index+1 , k)) return true;            sumT -= e[i].t;        }    }    return false;}void computing(){    dfs(1 , 0 , 1);    for(int i = 0; i <= route; i++) vis[way[i]] = 1;    DP(1 , 1);    if(sumT > T){        printf("Human beings die in pursuit of wealth, and birds die in pursuit of food!\n");        return;    }    T -= sumT;    for(int i = 0; i <= route; i++){        for(int t = T; t >= 0; t--){            if(ans[t] == 0 && t != 0) continue;            for(int j = T; j >= 0; j--){                if(t+j <= T && ans[t+j] < ans[t]+dp[way[i]][j]) ans[t+j] = ans[t]+dp[way[i]][j];            }        }    }    int Max = 0;    for(int i = 0; i <= T; i++) if(Max < ans[i]) Max = ans[i];    printf("%d\n" , Max);}int main(){    while(~scanf("%d%d" , &N , &T)){        initial();        readcase();        computing();    }    return 0;}

hdu 4276 The Ghost Blows Light(DP-树形DP)


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