![https://leetcode.com/problems/kth-largest-element-in-an-array/]
Find the kth largest element in an unsorted array. Note that it is the kth largest element in the sorted order, not the kth distinct element.
Example 1:
Input: [3,2,1,5,6,4] and k = 2
Output: 5
Example 2:
Input: [3,2,3,1,2,4,5,5,6] and k = 4
Output: 4
Note:
- You may assume k is always valid, 1 ≤ k ≤ array’s length.
class Solution {
public int findKthLargest(int[] nums, int k) {
int lo = 0;
int hi = nums.length - 1;
k = nums.length - k;
while (lo < hi) {
int j = partition(nums, lo, hi);
if (j < k) {
lo = j + 1;
} else if (j > k) {
hi = j - 1;
} else {
return nums[k];
}
}
return nums[k];
}
int partition(int[] a, int lo, int hi) {
int i = lo;
int j = hi + 1;
while (true) {
while (a[++i] < a[lo]) {
if (i == hi) break;
}
while (a[lo] < a[--j]) {
if (j == lo) break;
}
if (i >= j) break;
swap(a, i, j);
}
swap(a, lo, j);
return j;
}
void swap(int[] a, int i, int j) {
int temp = a[i];
a[i] = a[j];
a[j] = temp;
}
}