HDU-2159

 1 #include <cstdio>
 2 #include <cstring>
 3 #include <iostream>
 4 #include <algorithm>
 5 #define INF 0x3f3f3f3f
 6 #define MOD 1000000007
 7 using namespace std;
 8 typedef long long LL;
 9 
10 int ex, pat, kind, num;
11 const int maxn = 1e2 + 5;
12 int dp[maxn][maxn];
13 int gt[maxn], lose[maxn];
14 
15 void solve() {
16     memset(dp, 0, sizeof(dp));
17     for (int k = 0; k < kind; k++) {
18         for (int i = lose[k]; i <= pat; i++) {
19             for (int j = 1; j <= num; j++) {
20                 dp[i][j] = max(dp[i][j], dp[i - lose[k]][j - 1] + gt[k]);
21             }
22         }
23     }
24     /*
25     for (int i = 1; i <= pat; i++) {
26         for (int k = 0; k < kind; k++) {
27             for (int j = 1; j <= num; j++) {
28                 if (i >= lose[k])
29                 dp[i][j] = max(dp[i - lose[k]][j - 1] + gt[k], dp[i][j]);
30             }
31         }
32     }
33      */
34     int i;
35     for (i = 1; i <= pat; i++) {
36         if (dp[i][num] >= ex) {
37             printf("%d\n", pat - i);
38             break;
39         }
40     }
41     if (i == pat + 1) puts("-1");
42 }
43 
44 
45 int main(int argc, const char * argv[]) {
46     while (~scanf("%d%d%d%d", &ex, &pat, &kind, &num)) {
47         for (int i = 0; i < kind; i++) {
48             scanf("%d%d", &gt[i], &lose[i]);
49         }
50         solve();
51     }
52     return 0;
53 }