PAT 1040. Longest Symmetric String

#include<iostream>
#include<cstdio>
#include<string>
#include<cstring>
#include<queue>
#include<vector>
#include<cmath>
#include<iomanip>
#include<algorithm>
using namespace std;

//回文有两种情况:aba或者abba,即有对称点和无对称点。
int getSymLen(char *str,int pos)
{
	int len = strlen(str);
	int iCount1 = 0,low,high;

	//处理aba的情况
	low = pos - 1;
	high = pos + 1;
	while(low>=0 && high<len && str[low] == str[high])
	{
		iCount1++;
		low--;
		high++;
	}
	int len1 = 2*iCount1+1;

	//处理abba的情况;
	int iCount2 = 0;
	low = pos;
	high = pos + 1;
	while(low>=0 && high<len && str[low] == str[high])
	{
		iCount2++;
		low--;
		high++;
	}
	int len2 = 2*iCount2;
	return len1>len2?len1:len2;
}

int main()
{
	char str[1005];
	gets(str);
	int maxLen = 1,t,i;
	int len = strlen(str);
	for(i=0; i<len; i++)
	{
		t = getSymLen(str,i);
		if(t > maxLen)
			maxLen = t;
	}
	cout<<maxLen<<endl;
	return 0;
}

  

posted @ 2012-12-16 09:50  Frank@609  Views(512)  Comments(0Edit  收藏  举报