洛谷 P1542 包裹快递

题目传送门

解题思路:

二分答案,按照题目要求模拟验证,但数据太毒,要用long double.

AC代码:

#include<iostream>
#include<cstdio>

using namespace std;

long double l,r = 1e9,mid,ans;
int n;
struct kkk {
    long double x,y,z;
}e[200001];

inline bool check(long double len) {
    long double now = 0;
    for(int i = 1;i <= n; i++) {
        now += e[i].z / len;
        if(now > e[i].y) return false;
        if(now < e[i].x) now = e[i].x;    
    }
    return true;
}

int main() {
    scanf("%d",&n);
    for(int i = 1;i <= n; i++) 
        scanf("%Lf%Lf%Lf",&e[i].x,&e[i].y,&e[i].z);
    while(r - l >= 0.0001) {
        mid = (l + r) / 2;
        if(check(mid))
            r = mid,ans = mid;
        else
            l = mid;
    }
    printf("%.2Lf",ans);
    return 0;
}