BSOJ1040 -- 【练习题目】美元DOLLARS

#include<bits/stdc++.h>
using namespace std;
#define why 105
int n,a[why];
double f[why][2];
inline int redn()
{
	int ret=0,f=1;
	char ch=getchar();
	while(!isdigit(ch))
	{
		f=(ch!=‘-‘)?f:-f;
		ch=getchar();
	}
	while(isdigit(ch))
	{
		ret=ret*10+ch-‘0‘;
		ch=getchar();
	}
	return f>0?ret:-ret;
}
int main()
{
	n=redn();
	for(int i=1;i<=n;++i)a[i]=redn();
	f[1][0]=100;
	f[1][1]=a[1];
	for(int i=2;i<=n;++i)
	{
		f[i][0]=max(f[i-1][0],f[i-1][1]/a[i]*100.);
		f[i][1]=max(f[i-1][1],f[i-1][0]/100.*a[i]);
	}
	printf("%.2lf",max(f[n][0],f[n][1]/a[n]*100.));
	return 0;
}

#include<bits/stdc++.h>
using namespace std;
#define why 105
int n,a;
double f0=100.,f1,f;
inline int redn()
{
	int ret=0,f=1;
	char ch=getchar();
	while(!isdigit(ch))
	{
		f=(ch!=‘-‘)?f:-f;
		ch=getchar();
	}
	while(isdigit(ch))
	{
		ret=ret*10+ch-‘0‘;
		ch=getchar();
	}
	return f>0?ret:-ret;
}
int main()
{
	n=redn();
	a=redn();
	f1=a;
	for(int i=2;i<=n;++i)
	{
		a=redn();
		f=f0;//f0会被修改，用f存值
		f0=max(f0,f1/a*100.);
		f1=max(f1,f/100.*a);
	}
	printf("%.2lf",max(f0,f1/a*100.));
	return 0;
}