HDU 2594 Simpsons’ Hidden Talents

Simpsons’ Hidden Talents

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 10240    Accepted Submission(s): 3567

Problem Description

Homer: Marge, I just figured out a way to discover some of the talents we weren’t aware we had.
Marge: Yeah, what is it?
Homer: Take me for example. I want to find out if I have a talent in politics, OK?
Marge: OK.
Homer: So I take some politician’s name, say Clinton, and try to find the length of the longest prefix
in Clinton’s name that is a suffix in my name. That’s how close I am to being a politician like Clinton
Marge: Why on earth choose the longest prefix that is a suffix???
Homer: Well, our talents are deeply hidden within ourselves, Marge.
Marge: So how close are you?
Homer: 0!
Marge: I’m not surprised.
Homer: But you know, you must have some real math talent hidden deep in you.
Marge: How come?
Homer: Riemann and Marjorie gives 3!!!
Marge: Who the heck is Riemann?
Homer: Never mind.
Write a program that, when given strings s1 and s2, finds the longest prefix of s1 that is a suffix of s2.

 

Input

Input consists of two lines. The first line contains s1 and the second line contains s2. You may assume all letters are in lowercase.

 

Output

Output consists of a single line that contains the longest string that is a prefix of s1 and a suffix of s2, followed by the length of that prefix. If the longest such string is the empty string, then the output should be 0.
The lengths of s1 and s2 will be at most 50000.

 

Sample Input

clintonhomerriemannmarjorie

 

Sample Output

0rie 3

 

Source

HDU 2010-05 Programming Contest

 

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字符串hash水题

ac代码：

#include <cstdio>#include <cmath>#include <cstring>#include <string>#include <algorithm>#define ull unsigned long longusing namespace std;const int maxn=50000+10;const int base=163;char s1[maxn],s2[maxn],s3[maxn];ull hash1[maxn],hash2[maxn],p[maxn];  void INIT(){/*打一下表，方便区间取值*/ p[0]=1;for(int i=1;i<maxn;i++)p[i]=p[i-1]*base;}  ull get(int l,int r,ull *g){/*标准区间取值函数，改变了一个l > r,我也不知道对不对，这里我临时加的*/ if(l > r)return 0;return g[r]-g[l-1]*p[r-l+1];}int main(){INIT();while(~scanf("%s%s",s1+1,s2+1)){hash1[0]=hash2[1]=0;int cnt1=strlen(s1+1),cnt2=strlen(s2+1);for(int i=1;i<=cnt1;i++){/*进行hash*/ hash1[i]=hash1[i-1]*base+s1[i]-'a';}for(int i=1;i<=cnt2;i++){/*进行hash*/hash2[i]=hash2[i-1]*base+s2[i]-'a';}/*ans最大取他俩之间较小的长度*/ int ans=min(cnt1,cnt2);while(ans >= 0){/*进行一个个比较*/ ull a1=get(1,ans,hash1);ull a2=get(cnt2-ans+1,cnt2,hash2);if(a1 == a2){break ;}ans--;}/*输出*/ if(ans == 0) printf("%d\n",ans);else {for(int i=1;i<=ans;i++) printf("%c",s1[i]);printf(" %d\n",ans);}}return 0;}