UVA 1584 Circular Sequence【串的最小循环表示】

 

Circular Sequence
Time Limit:3000MS Memory Limit:0KB 64bit IO Format:%lld & %llu
Submit

Description

 
Some DNA sequences exist in circular forms as in the following figure, which shows a circular sequence ``CGAGTCAGCT", that is, the last symbol ``T" in ``CGAGTCAGCT" is connected to the first symbol ``C". We always read a circular sequence in the clockwise direction.
\epsfbox{p3225.eps}
Since it is not easy to store a circular sequence in a computer as it is, we decided to store it as a linear sequence. However, there can be many linear sequences that are obtained from a circular sequence by cutting any place of the circular sequence. Hence, we also decided to store the linear sequence that is lexicographically smallest among all linear sequences that can be obtained from a circular sequence.
Your task is to find the lexicographically smallest sequence from a given circular sequence. For the example in the figure, the lexicographically smallest sequence is ``AGCTCGAGTC". If there are two or more linear sequences that are lexicographically smallest, you are to find any one of them (in fact, they are the same).

 

input

The input consists of T test cases. The number of test cases T is given on the first line of the input file. Each test case takes one line containing a circular sequence that is written as an arbitrary linear sequence. Since the circular sequences are DNA sequences, only four symbols, A, C, G and T, are allowed. Each sequence has length at least 2 and at most 100.

Output

Print exactly one line for each test case. The line is to contain the lexicographically smallest sequence for the test case.
The following shows sample input and output for two test cases.

Sample Input

2
CGAGTCAGCT
CTCC

Sample Output

AGCTCGAGTC
CCCT

串的最小循环表示；

AC代码：

#include<cstdio>
#include<cstring> 
#include<algorithm>

using namespace std;

char str[222];

int MR(char *str,int len)
{
	int i=0,j=1,k=0;
	while(i<len&&j<len&&k<len) {
		 int t=str[(i+k)%len]-str[(j+k)%len];
		 if(!t) ++k;
		 else {
		      if(t>0)  i=i+k+1;
		      else j=j+k+1;
		      if(i==j) ++j;
		      k=0;
		 }
	}
	return  min(i,j);
}
int main()
{
	int T;
	scanf("%d",&T);
	while(T--)
	{
		scanf("%s",str);
		int len=strlen(str);
		int t=MR(str,len);
		int i=t;
		while(i<len) printf("%c",str[i++]);
		i=0;
		while(i<t) printf("%c",str[i++]);
		putchar('\n');
	}
	return 0;
 }