【HDOJ】2037 今年暑假不AC

qsort排序后DP，水题。注意，数组开大点儿，把时间理解为0~23，开太小会wa。

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

#define MAXNUM 100

int comp(const void *a, const void *b) {
    return *(int *)a - *(int *)b;
}

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

int main() {
    int time[MAXNUM][2], n;
    int i, j, end;
    int num[MAXNUM];

    while (scanf("%d", &n) != EOF && n) {
        end = 0;
        for (i=0; i<n; ++i) {
            scanf("%d %d", &time[i][0], &time[i][1]);
            if (time[i][1] > end)
                end = time[i][1];
        }

        qsort(time, n, sizeof(int)*2, comp);
        memset(num, 0, sizeof(num));

        for (i=0; i<n; ++i) {
            if (num[time[i][0]]+1 > num[time[i][1]]) {
                num[time[i][1]] = num[time[i][0]]+1;
                for (j=time[i][1]; j<=end; ++j) {
                    num[j] = mymax(num[j], num[time[i][1]]);
                }
            }
        }

        printf("%d
", num[end]);
    }


    return 0;
}