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
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1 #include <iostream> 2 #include <cstring> 3 #include <algorithm> 4 #include <map> 5 #define INF 0x3fffffff 6 using namespace std; 7 int book[10000+1]; 8 int f(int now_size,map<int,int> & dict){ 9 if(book[now_size] == -1){ 10 int ans = INF; 11 for(map<int,int> :: iterator it = dict.begin(); it != dict.end(); it++){ 12 if(it->second <= now_size){ 13 ans = min(ans,f(now_size - it->second,dict) + it->first); 14 } 15 } 16 book[now_size] = ans; 17 } 18 return book[now_size]; 19 } 20 int main(){ 21 int t,empty,full; 22 cin >> t; 23 while(t--){ 24 memset(book,-1,sizeof(book)); 25 book[0] = 0; 26 cin >> empty >> full; 27 if(full < empty)cout<<"This is impossible."<<endl; 28 else if(full == empty)cout<<"The minimum amount of money in the piggy-bank is 0."<<endl; 29 else{ 30 int coins_weight = full - empty; 31 int type; 32 cin >> type; 33 map<int,int> dict; 34 int v,w; 35 for(int i = 1; i <= type; i++){ 36 cin >> v >> w; 37 if(dict.count(v)){ 38 if(w < dict[v]) 39 dict[v] = w; 40 }else dict[v] = w; 41 } 42 int p = f(coins_weight,dict); 43 if(p ！= INF){ 44 cout << "The minimum amount of money in the piggy-bank is " << p << "." << endl; 45 }else{ 46 cout<<"This is impossible."<<endl; 47 } 48 } 49 } 50 return 0; 51 }
正解是完全背包来做。
1 #include <iostream> 2 #define INF 0x3fffffff 3 using namespace std; 4 struct node{ 5 int v; 6 int w; 7 }; 8 int main(){ 9 int t; 10 cin >> t; 11 while(t--){ 12 int dp[10000 + 1]; 13 node arr[501]; 14 int empty,full; 15 cin >> empty >> full; 16 int n,flag = 1; 17 cin >> n; 18 for(int i = 1; i <= n; i++) 19 cin >> arr[i].v >> arr[i].w; 20 21 if(empty == full)cout<<"The minimum amount of money in the piggy-bank is 0."<<endl; 22 else if(empty > full)cout<<"This is impossible."<<endl; 23 else flag = 0; 24 if(flag)continue; 25 int size = full - empty; 26 fill(dp,dp+size+1,INF); 27 dp[0] = 0; 28 for(int i = 1; i <= n; i++) 29 for(int j = arr[i].w; j <= size; j++){ 30 dp[j] = min(dp[j],dp[j-arr[i].w] + arr[i].v); 31 } 32 if(dp[size] == INF)cout<<"This is impossible."<<endl; 33 else cout<<"The minimum amount of money in the piggy-bank is "<<dp[size]<<"."<<endl; 34 } 35 return 0; 36 }