二分答案的条件

#include <bits/stdc++.h>
using namespace std;

int main() {
vector<int>a{2,3,5};
auto need=[&](int cap){int days=1,load=0;for(int x:a){if(x>cap)return 100;if(load+x>cap){++days;load=0;}load+=x;}return days;};
int lo=5,hi=10;while(lo<hi){int mid=(lo+hi)/2;if(need(mid)<=2)hi=mid;else lo=mid+1;}
cout<<lo<<" "<<need(10);
}

#include <bits/stdc++.h>
using namespace std;

int main() {
vector<int>a{2,3,5};
auto need=[&](int cap){int days=1,load=0;for(int x:a){if(x>cap)return 100;if(load+x>cap){++days;load=0;}load+=x;}return days;};
int lo=5,hi=10;while(lo<hi){int mid=(lo+hi)/2;if(need(mid)<=2)hi=mid;else lo=mid+1;}
cout<<lo<<" "<<need(10);
}