FindKthLargest.java

public int findKthLargest(int[] nums, int k) {
    return quickSelect(nums, 0, nums.length - 1, nums.length - k);
}
private int quickSelect(int[] nums, int l, int r, int k) {
    int p = partition(nums, l, r);
    if (p < k) return quickSelect(nums, p + 1, r, k);
    if (p > k) return quickSelect(nums, l, p - 1, k);
    return nums[p];
}
private int partition(int[] nums, int l, int r) {
    int pivot = nums[r];
    int p = r;
    for (int i = l; i < p; i++) {
        if (nums[i] > pivot) {
            swap(nums, i, p - 1);
            swap(nums, p, p - 1);
            i--;
            p--;
        }
    }
    return p;
}
private void swap(int[] nums, int a, int b) {
    int tmp = nums[a];
    nums[a] = nums[b];
    nums[b] = tmp;
}