java-递归判断数组是否升序


public class IsAccendListRecursive {

	/*递归判断数组是否升序
	 * if a Integer array is ascending,return true
	 * use recursion
	 */
	
	public static void main(String[] args){
		IsAccendListRecursive is=new IsAccendListRecursive();
		int[][] a={
				{1,2,3,4,5,6,7},
				{8,2,3,4,5,6,7},
				{1,2,3,8,5,6,7},
				{1,2,3,4,5,6,0},
		};
		for(int[] b:a){
			is.isAccendListRecursive3(b,0,b.length-1);
			System.out.println(is.result);
		}
	}
	
	
	
	//wrong answer
	public boolean isAccendListRecursive(int[] a,int s,int e){
		boolean re=false;
		if(s==e){		//one element
			re=true;
		}else if(s==e-1){//two elements
			re=a[s]<a[e];
		}else{
			re=isAccendListRecursive(a,s+1,e);
		}
		return re;
	}
	
	//look at this--(a[s]<a[s+1])--is it recursion any more?
	public boolean isAccendListRecursive2(int[] a,int s,int e){
		boolean re=false;
		if(s==e){
			re=true;
		}else{
			re=a[s]<a[s+1]&&isAccendListRecursive2(a,s+1,e);
		}
		return re;
	}
	
	private boolean result;
	//return the min element of the array that has been checked
	public int isAccendListRecursive3(int[] a,int s,int e){
		if(s==e){
			result=true;
		}else{
			int min=isAccendListRecursive3(a,s+1,e);
			result=result&&(a[s]<min);
		}
		return a[s];
	}
}

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