VJ

https://vjudge.net/contest/353157#problem/A

一开始用的记忆化搜索= =

样例能过不知道为啥提交WA

= 。=    = 。=

#include <iostream>
#include <cstring>
#include <algorithm>
#include <map>
#define INF 0x3fffffff
using namespace std;
int book[10000+1];
int f(int now_size,map<int,int> & dict){
    if(book[now_size] == -1){
        int ans = INF;
        for(map<int,int> :: iterator it = dict.begin(); it != dict.end(); it++){
            if(it->second <= now_size){
                ans = min(ans,f(now_size - it->second,dict) + it->first);
            }
        }
        book[now_size] = ans;
    }
    return book[now_size];
}
int main(){
    int t,empty,full;
    cin >> t;
    while(t--){
        memset(book,-1,sizeof(book));
        book[0] = 0;
        cin >> empty >> full;
        if(full < empty)cout<<"This is impossible."<<endl;
        else if(full == empty)cout<<"The minimum amount of money in the piggy-bank is 0."<<endl;
        else{
            int coins_weight = full - empty;
            int type;
            cin >> type;
            map<int,int> dict;
            int v,w;
            for(int i = 1; i <= type; i++){
                cin >> v >> w;
                if(dict.count(v)){
                    if(w < dict[v])
                        dict[v] = w;
                }else dict[v] = w;
            }
            int p = f(coins_weight,dict);
            if(p ！= INF){
                cout << "The minimum amount of money in the piggy-bank is " << p << "." << endl;
            }else{
                cout<<"This is impossible."<<endl;
            }
        }
    }
    return 0;
}

正解是完全背包来做。

#include <iostream>
#define INF 0x3fffffff
using namespace std;
struct node{
    int v;
    int w;
};
int main(){
    int t;
    cin >> t;
    while(t--){
        int dp[10000 + 1];
        node arr[501];
        int empty,full;
        cin >> empty >> full;
        int n,flag = 1;
        cin >> n;
        for(int i = 1; i <= n; i++)
            cin >> arr[i].v >> arr[i].w;
        
        if(empty == full)cout<<"The minimum amount of money in the piggy-bank is 0."<<endl;
        else if(empty > full)cout<<"This is impossible."<<endl;
        else flag = 0;
        if(flag)continue;
        int size = full - empty;
        fill(dp,dp+size+1,INF);
        dp[0] = 0;
        for(int i = 1; i <= n; i++)
            for(int j = arr[i].w; j <= size; j++){
                dp[j] = min(dp[j],dp[j-arr[i].w] + arr[i].v);
            }
        if(dp[size] == INF)cout<<"This is impossible."<<endl;
        else cout<<"The minimum amount of money in the piggy-bank is "<<dp[size]<<"."<<endl;
    }
    return 0;
}