Constructing Roads In JGShining's Kingdom（HDU1025）（LCS序列的变行）

Constructing Roads In JGShining's Kingdom  HDU1025

 

题目主要理解要用LCS进行求解！

并且一般的求法会超时！！要用二分！！！

最后蛋疼的是输出格式的注意（直接报错误！！！）

#include<iostream>
#include<stdio.h>
#include<algorithm>
#include<string.h>
using namespace std;
int a[500005],dp[500005];
int main()
{
    int n,i,a1,b1,len,j,d=0,left,right,mid;
    while(scanf("%d",&n)!=EOF)
    {
        for(i=0;i<n;i++)
        {
            scanf("%d%d",&a1,&b1);
            a[a1]=b1;
        }
        dp[0]=-1;
        len=0;
        for(i=1;i<=n;i++)
        {
           if(dp[len]<=a[i])
           {
               len++;
               dp[len]=a[i];
           }
           else
           {
               left=0;
               right=len;
               while(right-left>1)
               {
                   mid=(left+right)/2;
                   if(a[i]>dp[mid])
                    left=mid;
                   else
                    right=mid;
               }
               dp[right]=a[i];
           }
        }
        printf("Case %d:\n",++d);
        if(len>1)
            printf("My king, at most %d roads can be built.\n\n",len);
        else
            printf("My king, at most %d road can be built.\n\n",len);//没有这个，直接报错误！！！找了好久啊。。。
    }
    return 0;
}