HDU 3294 Girl's research(最长回文子串)

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////  main.cpp//  Richard////  Created by 邵金杰 on 16/9/27.//  Copyright © 2016年 邵金杰. All rights reserved.//#include<iostream>#include<cstdio>#include<cstring>#include<algorithm>using namespace std;const int maxn=200000+100;char s[maxn*2];int p[maxn*2];int main(){    char c;    while(scanf("%c %s",&c,s)!=EOF)    {        int len=(int)strlen(s);        for(int i=len;i>=0;i--){            s[i+i+2]=s[i];            s[i+i+1]='#';        }        s[0]='*';        int id=0,maxlen=0,pos=0;        for(int i=2;i<2*len+1;i++)        {            if(p[id]+id>p[i]+i) p[i]=min(p[id*2-i],p[id]+id-i);            else p[i]=1;            while(s[i+p[i]]==s[i-p[i]]) p[i]++;            if(p[i]+i>p[id]+id) id=i;            if(maxlen<p[i]) {maxlen=p[i];pos=i;}        }        if(maxlen-1==1) {printf("No solution!\n");continue;}        int x='a'-c;        cout<<(pos-maxlen+1+1)/2-1<<" "<<(pos+maxlen-1-1)/2-1<<endl;        for(int i=(pos-maxlen+1+1);i<=(pos+maxlen-1-1);i++)            if(s[i]!='#') printf("%c",((s[i]+x)>='a')?(s[i]+x):(s[i]+x+26));printf("\n");        getchar();    }    return 0;}

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