Leetcode56 合并区间

public int[][] merge(int[][] arr) {
        //根据第一个元素排序,快速排序
        if(arr.length == 0)
            return new int[0][0];
        if(arr.length == 1)
            return arr;
        boolean[] isvristed = new boolean[arr.length];
        for(int i= 0 ; i < isvristed.length ; i++)
        {
            isvristed[i] = false;
        }
        
        List<int[]> list = new ArrayList<>();
         boolean flag = false;
        quickSort(arr,0,arr.length-1);
        int i = 0;
        
        while(i< arr.length && i+1<arr.length) {
            
            int[] num1 = arr[i];
            int[] num2 = arr[i+1];
            isvristed[i] = true;
            
            isvristed[i+1] = true;
            while(true)
            {
                
                if(num1[1] >= num2[0])
                {
                    num1 = new int[] {num1[0] , Math.max(num1[1], num2[1])};
                    i++;
                    arr[i] = num1;
                    flag = true;
                }
                else
                {
                flag = false;    
                    break;
                }
                if(i< arr.length && i+1<arr.length)
                {
                    num1 = arr[i];
                    num2 = arr[i+1];
                    isvristed[i] = true;
                    isvristed[i+1] = true;
                }
                else
                {
                    break;
                }
                
            }
            list.add(num1);
            
            i++;
        }
        if(flag == false)
        {
            list.add(arr[arr.length-1]);
        }
        
        int[][] ans = new  int[list.size()][2];
        
        int index = 0;
        for(int[] a : list)
        {
            ans[index][0] = a[0];
            ans[index][1] = a[1];
            index++;
            
        }
        return ans;

    }
    private  void quickSort(int[][] arr, int low, int high) {

        if (low < high) {
            
            int index = quickSorts(arr,low,high);
            quickSort(arr, low, index - 1);
            quickSort(arr, index + 1, high);
        }

    }
    public   int quickSorts(int[][] arr,int l , int r)
    {
        /**
        *1,设置锚点
        *2,定义左右边界
        **/
        int[] curArr  = arr[l];
        int curValue =  curArr[0];

        

        while(l < r)
        {
            while(l < r && arr[r][0] >= curValue)
            {
                r--;
            }
            if(l < r)
            {
                arr[l] = arr[r];
                l++;
            }
            
            while(l < r && arr[l][0] <=curValue)
            {
                l++;
            }
            if(l < r)
            {
                arr[r] = arr[l];
                r--;
            }
            
        }
        arr[r] = curArr;
        return r;
        
    }