利用传统的完全背包解法会超时，下面代码超时
1 #include <iostream> 2 #include <vector> 3 #include <algorithm> 4 5 #define INF 1<<30 6 using namespace std; 7 8 int main(){ 9 int T; 10 cin >> T; 11 while(T--){ 12 int E,F; 13 cin >>E>>F; 14 int pigWeight =F-E; 15 int n; 16 cin >> n; 17 vector<int> p(n),w(n); 18 for(int i = 0; i < n; i ++ ){ 19 cin >> p[i]>>w[i]; 20 } 21 vector<int> dp(pigWeight+1,INF); 22 dp[0]=0; 23 for(int i = 0; i < n; i ++ ){ 24 for(int j = w[i]; j <= pigWeight; j ++){ 25 for(int k =0; k <= j/w[i]; k ++){ 26 dp[j] = min(dp[j],dp[j-w[i]]+p[i]); 27 } 28 } 29 } 30 if(dp[pigWeight] == INF) cout<<"This is impossible."<<endl; 31 else cout<<"The minimum amount of money in the piggy-bank is "<<dp[pigWeight]<<"."<<endl; 32 33 } 34 35 return 0; 36 }
需要对完全背包进行优化，具体参考背包九讲 和 http://blog.csdn.net/wumuzi520/article/details/7014830
优化后代码
1 #include <iostream> 2 #include <vector> 3 #include <algorithm> 4 5 #define INF 1<<30 6 using namespace std; 7 8 int main(){ 9 int T; 10 cin >> T; 11 while(T--){ 12 int E,F; 13 cin >>E>>F; 14 int pigWeight =F-E; 15 int n; 16 cin >> n; 17 vector<int> p(n),w(n); 18 for(int i = 0; i < n; i ++ ){ 19 cin >> p[i]>>w[i]; 20 } 21 vector<int> dp(pigWeight+1,INF); 22 dp[0]=0; 23 for(int i = 0; i < n; i ++ ){ 24 for(int j = w[i]; j <= pigWeight; j ++){ 25 dp[j] = min(dp[j],dp[j-w[i]]+p[i]); 26 } 27 } 28 if(dp[pigWeight] == INF) cout<<"This is impossible."<<endl; 29 else cout<<"The minimum amount of money in the piggy-bank is "<<dp[pigWeight]<<"."<<endl; 30 } 31 32 return 0; 33 }