HDU 4883 TIANKENG’s restaurant(区间选点)

HDU 4883 TIANKENG’s restaurant

题目链接

题意：给定一些时间作为区间，和一个人数，问要安排多少人去看管（一个人只能看管一个人)

思路：普通的区间选点问题，一个区间拆成一个进入点一个出去点，然后排序循环求答案即可

代码：

#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;

const int N = 20005;
struct Man {
int v, t;
Man() {}
Man(int v, int t) {this->v = v; this->t = t;}
} m
;

bool cmp(Man a, Man b) {
if (a.t != b.t)
return a.t < b.t;
return a.v < b.v;
}

int n, t, mn;

int main() {
scanf("%d", &t);
while (t--) {
mn = 0;
scanf("%d", &n);
for (int i = 0; i < n; i++) {
int a, b, c, d, e;
scanf("%d%d:%d%d:%d", &a, &b, &c, &d, &e);
int t1 = b * 60 + c;
int t2 = d * 60 + e;
m[mn++] = Man(a, t1);
m[mn++] = Man(-a, t2);
}
sort(m, m + mn, cmp);
int ans = 0, sum = 0;
for (int i = 0; i < mn; i++) {
sum += m[i].v;
ans = max(ans, sum);
}
printf("%d\n", ans);
}
return 0;
}