这是WA 5个点的

#include<bits/stdc++.h>
#define int long long int
using namespace std;
const int N=1000005;
int n,a[N];
double d=100.0,m=0.0;
signed main(){
	cin.tie(0);cout.tie(0);
    cin>>n;
    for(int i=1;i<=n;i++)
        cin>>a[i];
    a[n+1]=2147483647;
    for(int i=1;i<=n;i++)
    {
        if(a[i-1]<a[i]&&a[i]>a[i+1])
            m=(d/100.0)*a[i];
        if(a[i-1]>a[i]&&a[i]<a[i+1])
            d=(m/a[i]*1.0)*100.0;
    }
    printf("%.2lf",d);
	return 0;
}

这是AC的

#include<bits/stdc++.h>
#define int long long int
using namespace std;
const int N=1000005;
int n,a[N];
double d=100.0,m=0.0;
signed main(){
	cin.tie(0);cout.tie(0);
    cin>>n;
    for(int i=1;i<=n;i++)
        cin>>a[i];
    a[n+1]=2147483647;
    for(int i=1;i<=n;i++)
    {
        if(a[i-1]<=a[i]&&a[i]>=a[i+1])
            m=(d/100.0)*a[i];
        if(a[i-1]>=a[i]&&a[i]<=a[i+1])
            d=(m/a[i]*1.0)*100.0;
    }
    printf("%.2lf",d);
	return 0;
}