查找数组中第K大的数字

KthLargest

public int findKthLargest(int[] nums, int k){
        int index = searchIndex(nums, 0, nums.length-1, k);
        return nums[index];
    }

    public int partition(int[] nums, int low, int high){
        int key=nums[low];

        while(low < high){
            // 大到小排序
            while(low<high && nums[high]<=key){
                high--;
            }
            nums[low] = nums[high];

            while(low<high && nums[low]>=key){
                low++;
            }
            nums[high] = nums[low];
        }
        
        nums[low] = key;
        return low;
    }
    
    public int searchIndex(int[] nums, int x, int y, int k){
        int index=partition(nums, x, y);
        if(index == k-1){
            return index;
        }else if(index > k-1){
            return searchIndex(nums, x, index-1, k);
        }else {
            return searchIndex(nums, index+1, y, k);
        }
    }