POJ 1836

刚开始二分写错了 wa了很久 这个二分 的好好想想

#include <iostream>
#include<cstdio>
#include<string.h>
#include<cmath>
using namespace std;
const double eps=1e-10;
double dp[2005],L[2005],R[2005];
int n;
int BIN(int len,double x)
{
    int left=0,right=len-1,mid;
    while(left<right)
        {
            mid=(left+right)/2;
            if(x>L[mid])left=mid+1;
            else  right=mid;
        }
        return left;
}
int work(int li,int ri)
{
	int i,gh=0,pos;
    L[0]=dp[0];
	int len=1,sum=0,KH=0;
    for(i=n-1;i>=ri;i--)
        R[KH++]=dp[i];
    for(i=1;i<li+1;i++)
    {
        if(dp[i]>L[len-1])
		{
          L[len++]=dp[i];
		}
        else
        {
             pos=BIN(len,dp[i]);
            L[pos] =dp[i];
        }
    }
    sum=li+1-len;
	gh=0;
    len=1;
    L[0]=R[0];
    for( i=1;i<KH;i++)
    {
        if(R[i]>L[len-1] )
		{
			L[len++]=R[i];
        }
		else
        {
             pos=BIN(len,R[i]);
             L[pos] =R[i];
        }
    }
    sum+=KH-len;
    return sum;
}
int main()
{
    int maxn,kk,i;
    while(scanf("%d",&n)==1)
        {
            maxn=1000000;
            for(i=0;i<n;i++)
              scanf("%lf",&dp[i]);
            for( i=0;i<n-1;i++)
                if((kk=work(i,i+1))<maxn)maxn=kk;
                printf("%d
",maxn);
        }
    return 0;
}