HDU 2159 FATE

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <cmath>
 5 #include <algorithm>
 6 #include <climits>
 7 #include <vector>
 8 #include <queue>
 9 #include <cstdlib>
10 #include <string>
11 #include <set>
12 #include <stack>
13 #define LL long long
14 #define pii pair<int,int>
15 #define INF 0x3f3f3f3f
16 using namespace std;
17 const int maxn = 110;
18 int dp[maxn][maxn],n,m,k,s;
19 int a[maxn],b[maxn];
20 int main() {
21     while(~scanf("%d %d %d %d",&n,&m,&k,&s)) {
22         for(int i = 1; i <= k; ++i)
23             scanf("%d %d",a+i,b+i);
24         memset(dp,0,sizeof(dp));
25         for(int i = 1; i <= k; ++i) {
26             for(int j = 1; j <= s; ++j) {
27                 for(int k = b[i]; k <= m; ++k) {
28                     dp[k][j] = max(dp[k][j],dp[k-b[i]][j-1]+a[i]);
29                 }
30             }
31         }
32         if(dp[m][s] < n) puts("-1");
33         else {
34             for(int i = 0; i <= m; ++i)
35                 if(dp[i][s] >= n) {
36                     printf("%d\n",m-i);
37                     break;
38                 }
39         }
40     }
41     return 0;
42 }