hdu1841 Find the Shortest Common Superstring -- (KMP 前缀，后缀处理)

最新推荐文章于 2017-08-15 11:42:23 发布

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本文探讨了两个字符串的最短公共超字符串问题，并提供了一种有效算法来解决该问题。通过KMP算法找到两个字符串间最长的重叠部分，进而得出最短公共超字符串的长度。

Find the Shortest Common Superstring

Time Limit: 1000/1000 MS (Java/Others) Memory Limit: 65535/65535 K (Java/Others)
Total Submission(s): 1693 Accepted Submission(s): 460

Problem Description

The shortest common superstring of 2 strings S₁ and S₂ is a string S with the minimum number of characters which contains both S₁ and S₂ as a sequence of consecutive characters. For instance, the shortest common superstring of “alba” and “bacau” is “albacau”.
Given two strings composed of lowercase English characters, find the length of their shortest common superstring.

Input

The first line of input contains an integer number T, representing the number of test cases to follow. Each test case consists of 2 lines. The first of these lines contains the string S₁ and the second line contains the string S₂. Both of these strings contain at least 1 and at most 1.000.000 characters.

Output

For each of the T test cases, in the order given in the input, print one line containing the length of the shortest common superstring.

Sample Input

2
alba
bacau
resita
mures

Sample Output

7
8

Author

Mugurel Ionut Andreica

#include <stdio.h>
#include <string.h>
#include <algorithm>
const int N = 1000005;
using namespace std;
char t[N],w[N];
int i,j,Next[N],sum,l;
void get_next(char *a,int len){
	Next[0]=-1;
	i=0;j=-1;
	while(i<len){
		if(j==-1||a[i]==a[j]) Next[++i]=++j;
		else j=Next[j];
	}
}
int KMP(char *a,char *b){
	int lena=strlen(a);
	int lenb=strlen(b);
	get_next(b,lenb);
	i=0;j=0;
	while(i<lena&&j<lenb){
		if(j==-1||b[j]==a[i]) i++,j++;
		else j=Next[j];
	}
	return j;
}
int main(){
	int n;
	scanf("%d",&n);
	while(n--){
		scanf("%s%s",&w,&t);
		//w主串
		int a=KMP(w,t);
		//printf("%d\n",a);
		int b=KMP(t,w);
		//printf("%d\n",b);
		printf("%d\n",strlen(w)+strlen(t)-max(a,b));
	}
	return 0;
}