专题三 · 1018

代码及解释

#include <iostream>
#include <climits>
#include <algorithm>

// 完全背包问题
// 应该很简单了，但是一直 WA ＝－＝
// 检查了好几遍，转移方程，循环边界都没问题

const size_t SIZE = 10005;

int p[SIZE];
int w[SIZE];
int dp[SIZE];

int main() {
int T;
std::cin>>T;

while(T--) {
int V1, V2;
std::cin >> V1 >> V2;
int V = V2-V1;

int N;
std::cin >> N;
for(int i = 0; i < N; ++i)
std::cin >> p[i] >> w[i];

for(int i = 0; i <= V; ++i)
dp[i] = INT_MAX;

dp[0] = 0;
for(int i = 0; i < N; ++i)
for(int j = w[i]; j <= V; ++j)
dp[j] = std::min(dp[j], dp[j-w[i]]+p[i]);

if(dp[V] == INT_MAX)
std::cout << "This is impossible." << std::endl;
else
std::cout << "The minimum amount of money in the piggy-bank is "
<< dp[V]
<< "."
<< std::endl;

}
}