【HDOJ】2159 FATE

DP+贪心优化。

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define MAXNUM 105

typedef struct {
    int exp, deg;
} info_st;

info_st infos[MAXNUM];
int dp[MAXNUM][MAXNUM];
int n, m, k, s;

int comp(const void *a, const void *b) {
    info_st *p = (info_st *)a;
    info_st *q = (info_st *)b;

    if (p->deg == q->deg)
        return q->exp - p->exp;
    else
        return p->deg - q->deg;
}

int mymax(int a, int b) {
    return a>b ? a:b;
}

int main() {
    int i, j, p, exp, deg;

    while (scanf("%d%d%d%d", &n, &m, &k, &s) != EOF) {
        for (i=0; i<k; ++i)
            scanf("%d %d", &infos[i].exp, &infos[i].deg);

        memset(dp, 0, sizeof(dp));
        qsort(infos, k, sizeof(info_st), comp);

        for (i=0; i<k; ++i) {
            exp = infos[i].exp;
            deg = infos[i].deg;
            if (i && deg == infos[i-1].deg) {
                continue;
            }
            for (j=1; j<=s; ++j) {
                for (p=deg; p<=m; ++p) {
                    dp[p][j] = mymax(dp[p][j], dp[p-deg][j-1]+exp);
                }
            }
        }

        for (i=1; i<=m; ++i) {
            if (dp[i][s] >= n)
                break;
        }

        if (i <= m)
            printf("%d\n", m-i);
        else
            printf("-1\n");
    }

    return 0;
}