The question
must be read carefully to understand the meaning of
the question. This question is to increase or decrease the energy based on the energy of the previous point e; formula: 2*eH(i)
Use dichotomous thinking to find the answer, the last l or r is the answer
#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;
const int N = 100010;
int n;
int h[N];
bool check(int e)
{
for (int i = 1; i <= n; i ++ )
{
e = e * 2 - h[i];
if (e >= 1e5) return true;//此处不能省略,因为如果一直乘2,则会出现溢出现象,e可能超级大变为负值
if (e < 0) return false;
}
return true;
}
int main()
{
scanf("%d", &n);
for (int i = 1; i <= n; i ++ ) scanf("%d", &h[i]);
int l = 0, r = 1e5;//设置高度的最小值和最大值
while (l < r)//对应二分的模板一 (AcWing 789. 数的范围)
{
int mid = l + r >> 1;
if (check(mid)) r = mid;
else l = mid + 1;
}
printf("%d\n", l);//二分结束时 l=r
return 0;
}