# 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];
}
}

```

java-递归判断数组是否升序

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