无法识别计数反转时的逻辑错误

Question

public static int countinv(int[]  arr, int low, int high){

if(low>=high){
    return 0;
}

int mid= (low+high)/2;
int leftans= countinv(arr, low, mid);
int rightans= countinv(arr, mid+1, high);
int split= mergeandcount(arr,low,mid,high);

    return leftans+rightans+split;
}
private static int mergeandcount(int[] arr, int low, int mid, int high) {
    int[] temp = new int[high-low+1];
    int k=0;int count =0;
    int i=low; int j= mid+1;
    while(i< mid&& j<high){
        if(arr[i]<=arr[j]){
            temp[k++]=arr[i++];
        }
        else{
            temp[k++]=arr[j++];
            count += mid-i;
        }
    }
    while(i<mid){
        temp[k++]=arr[i++];
    }
    while(j<high){
        temp[k++]=arr[j++];
    }   i=low;j=0;k=0;  
    while(i<high){
        arr[i++]=temp[k++];
    }


    return count;
}

请帮我识别出反转次数的逻辑错误。 它与geeksforgeeks几乎相同。但是我找不到一个。

如建议的那样，主要方法如下：     `

public static void main(String[] args) {

        int arr[] = {3,2,1};
        int j = countinv(arr,0,arr.length);
        System.out.println(j);
    }

在这种情况下，输出应为3。 它是倒数计数的问题。