循環移位算法的三種實現

1.普通算法

2.塊交換算法

3.求逆算法

public class Cyc_shift {
	static String str;
	public static void main(String[] args){
		str="12345";
		
		char[] str1=exchange(3,str.toCharArray());
		for(int i=0;i<str1.length;i++){
			System.out.print(str1[i]);
		}
	}
	
	/*普通算法*/
	public static char[] usually(int n,char[] str){
		char tmp;
		System.out.println(str.length);
		for(int i=0;i<n;i++){
			tmp=str[str.length-1];
			for(int j=str.length-1;j>0;j--){
				str[j]=str[j-1];
			}
			str[0]=tmp;
		}
		return str;
	}
	/*塊交換算法*/
	public static char[] exchange(int num,char[] str){
		int end=str.length;
		int start=0;
		int point=end-num;
		int m,n;
		while(point!=end && point!=start){
			m=point-start;
			n=end-point;
			change(point,min(m,n),str);
			if(m>=n){
				end=point;
				point=point-n;
			}else{
				start=point;
				point=point+m;
			}
		}
		return str;
	}
	public static char[] change(int point,int n,char[] str){
		char s;
		int tmp=n-1;
		for(int i=1;i<=n;i++){
			s=str[point-i];
			str[point-i]=str[point+tmp];
			str[point+tmp]=s;
			tmp--;
		}
		for(int i=0;i<str.length;i++){
			System.out.print(str[i]);
		}
		System.out.println("");
		return str;
	}
	public static int min(int m,int n){
		if(m>=n){
			return n;
		}else{
			return m;
		}
	}
	
	/*求逆算法*/
	public static char[] reverse(int a,int b,char[] str){
		char temp;
		while(true){
			temp =str[a];
			str[a]=str[b];
			str[b]=temp;
			a++;
			b--;
			if(a>=b)
				break;
		}
		return str;
	}
	public static char[] treverse(int n,char[] str){
		reverse(0,str.length-n-1,str);
		reverse(str.length-n,str.length-1,str);
		reverse(0,str.length-1,str);
		return str;
	}
}