leetcode215

class Solution {
    public int findKthLargest(int[] nums, int k) {
        //利用快排的思路也可以解决
        int k1=nums.length-k;
        int low=0,high=nums.length-1;
        while(low<high){
            int j=partition(nums,low,high);
            if(j==k1){
                break;
            }else if(j<k1){
                low=j+1;
            }else {
                high=j-1;
            }
        }
        return nums[k];
    }
    
    private static int partition(int [] a,int l,int h){
        int i=l,j=h+1;
        while(true){
            while (a[++i] < a[l] && i < h) ;
            while (a[--j] > a[l] && j > l) ;
          if (i >= j) {
            break;
        }
           swap(a,i,j);
        }
        swap(a,i,j);
        return j;
    }
    
    private static void swap(int[] a, int i, int j) {
    int t = a[i];
    a[i] = a[j];
    a[j] = t;
}
       
}