UVA1584Circular Sequence

寻找字典序最小环状DNA序列

最新推荐文章于 2021-12-24 09:56:02 发布

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本文介绍了一种算法，用于从给定的环状DNA序列中找到字典序最小的线性序列。通过旋转序列并比较字典序大小，确保找到的序列是最小的。最终输出该序列供进一步的生物信息学分析使用。

Some DNA sequences exist in circular forms as inthe following figure, which shows a circular sequence“CGAGTCAGCT”, that is, the last symbol “T” in“CGAGTCAGCT” is connected to the first symbol “C”. We alwaysread a circular sequence in the clockwise direction.

Since it is not easy to store a circular sequence in a computeras it is, we decided to store it as a linear sequence.However, there can be many linear sequences that are obtainedfrom a circular sequence by cutting any place of thecircular sequence. Hence, we also decided to store the linearsequence that is lexicographically smallest among all linearsequences that can be obtained from a circular sequence.

Your task is to find the lexicographically smallest sequencefrom a given circular sequence. For the example in the figure,the lexicographically smallest sequence is “AGCTCGAGTC”. If there are two or more linear sequences thatare 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 inputfile. Each test case takes one line containing a circular sequence that is written as an arbitrary linearsequence. Since the circular sequences are DNA sequences, only four symbols, ‘A’, ‘C’, ‘G’ and ‘T’, areallowed. 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 sequencefor the test case.

Sample Input

CGAGTCAGCT

CTCC

Sample Output

AGCTCGAGTC

CCCT

就是一个圈，然后弊端的判断字典序谁大（就是strcmp（）函数）

代码：

#include<stdio.h>
#include<string.h>
int main()
{
	char s[101],s1[101];
	char ch;
	int len,i,j,n;
	scanf("%d",&n);
	getchar();
	while(n--)
	{
		scanf("%s",s);
		strcpy(s1,s);
		len=strlen(s);
		for(j=0;j<len;j++)	
		{
			ch=s[0];	
			for(i=1;i<len;i++)		
				s[i-1]=s[i];
			s[len-1]=ch;	
			if(strcmp(s1,s)>0)
				strcpy(s1,s);				
		}
		puts(s1);
	}
	return 0;
}