HDU 1867 A+B for you again(简单kmp)-优快云博客

本文介绍了一个关于字符串处理的问题，即如何根据特定规则合并两个字符串。文章详细解释了问题背景及输入输出要求，并提供了一段C++代码实现，通过构建临时字符串并使用后缀数组的方法来确定合并后的最短字符串。

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A + B for you again

Time Limit: 5000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 8938 Accepted Submission(s): 2166

Problem Description

Generally speaking, there are a lot of problems about strings processing. Now you encounter another such problem. If you get two strings, such as “asdf” and “sdfg”, the result of the addition between them is “asdfg”, for “sdf” is the tail substring of “asdf” and the head substring of the “sdfg” . However, the result comes as “asdfghjk”, when you have to add “asdf” and “ghjk” and guarantee the shortest string first, then the minimum lexicographic second, the same rules for other additions.

Input

For each case, there are two strings (the chars selected just form ‘a’ to ‘z’) for you, and each length of theirs won’t exceed 10^5 and won’t be empty.

Output

Print the ultimate string by the book.

Sample Input

  asdf sdfg asdf ghjk
 

Sample Output

  asdfg asdfghjk
 

Author

Wang Ye

Source

2008杭电集训队选拔赛——热身赛

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#include<iostream>
#include<queue>
#include<stdio.h>
#include<string>
#include<cmath>
using namespace std;
typedef long long LL;
#define maxn (100001*2)
int Next[maxn];
/*
题意很简单，
几个点就是如何判断字典序，
还有就是截取的问题，，，

这题该打：：；我竟然忽略了最大前缀后缀可以覆盖其中一个串的情况，
处理方法是在中间添加一个分割符，，就可以了
*/
void getNext(string t)
{
    int k=-1,sz=t.size();
    Next[0]=-1;
    for(int i=1;i<sz;i++)
    {
        while(k>-1&&t[k+1]!=t[i])
            k=Next[k];
        if(t[k+1]==t[i])
            k++;
        Next[i]=k;//i-k
    }
}
int main()
{
    ios::sync_with_stdio(false);
    string s1,s2;
    while(cin>>s1>>s2)
    {
        string tmp1=s2+"#"+s1,tmp2=s1+"#"+s2;
        int len=tmp1.size();
        getNext(tmp1);
        int re1=Next[len-1]+1;
        getNext(tmp2);
        int re2=Next[len-1]+1;
        tmp1=s1+s2.substr(re1,s2.size()-re1);
        tmp2=s2+s1.substr(re2,s1.size()-re2);
        if(re1>re2)  cout<<tmp1;
        else if(re2>re1) cout<<tmp2;
        else
        {
            if(tmp1<tmp2) cout<<tmp1;
            else cout<<tmp2;
        }
        cout<<endl;
    }
    return 0;
}