蓝桥杯2022年第十三届决赛真题-卡牌——二分法

#include<iostream>
using namespace std;
long long int n, m;
long long int a[200010], b[200010];
bool check(int k)
{
  long long int count = 0;
  for (int i = 0; i < n; i++)
  {
    if (a[i] < k)
    {
      if (k - a[i] > b[i])
      {
        return false;
      }
      count += k - a[i];
    }
  }
  if (count > m)
  {
    return false;
  }
  else
  {
    return true;
  }
}
int main()
{
  cin >> n >> m;
  for (int i = 0; i < n; i++)
  {
    cin >> a[i];
  }
  for (int i = 0; i < n; i++)
  {
    cin >> b[i];
  }
  long long int left = 0, right = 20000000;
  while (left<right)
  {
    long long int mid = (left + right +1) / 2;
    if (check(mid) == true)
    {
      left = mid;
    }
    else
    {
      right = mid - 1;
    }
  }
  cout << right<< endl;
  return 0;
}