记录编号	169356	评测结果	AAAAAAAAA
题目名称	破碎的项链	最终得分	100
用户昵称	NVIDIA	是否通过	通过
代码语言	C++	运行时间	0.003 s
提交时间	2015-07-08 17:12:40	内存使用	0.29 MiB

#include<iostream>
#include<cstdlib>
#include<string>
#include<cstdio>
#include<algorithm>
using namespace std;
int b1[998],r1[998],b2[998],r2[998];
int n;char ch[998];
int M(int a,int b)
{
    if (a>b) return a;
    else return b;
}
int main()
{
    freopen("beads.in","r",stdin);
    freopen("beads.out","w",stdout);
    scanf("%d",&n);
    scanf("%s",ch);
    for (int i=0;i<n;i++) ch[i+n]=ch[i];
	//printf("%s\n",ch);
    b1[0]=r1[0]=0;
    for (int i=1;i<=n;i++)
        if (ch[i]=='b')
        {
            b1[i]=b1[i-1]+1;r1[i]=0;
        }
        else if (ch[i]=='r')
        {
            b1[i]=0;r1[i]=r1[i-1]+1;
        }
        else 
        {
            b1[i]=b1[i-1]+1;r1[i]=r1[i-1]+1;
        }
    b2[2*n+1]=r2[2*n+1]=0;
    for (int i=2*n;i>=1;i--)
        if (ch[i]=='b')
        {
            b2[i]=b2[i+1]+1;r2[i]=0;
        }
        else if (ch[i]=='r')
        {
            b2[i]=0;r2[i]=r2[i+1]+1;
        }
        else 
        {
            b2[i]=b2[i+1]+1;r2[i]=r2[i+1]+1;
        }
    int ans=0;
    for (int i=1;i<=2*n;i++)
        ans=M(M(b1[i],r1[i])+M(b2[i+1],r2[i+1]),ans);
    if (ans>n) ans=n;
    printf("%d\n",ans);
    return 0;
}