LeetCode_215_KthLargestElementinanArray
题目分析：
您还记得当年写过的快排吗？虽然不是最快的思路，确是本题的初衷。利用快排的操作，将问题分治。
解法：
public static int findKthLargest(int[] nums, int k) {
int left = 0, right = nums.length - 1;
while (true){
int pos = partition(nums, left, right);
if(k - 1 == pos) return nums[pos];
else if(pos > k - 1) right = pos - 1;
else left = pos + 1;
}
}
public static int partition(int[] nums, int left, int right){
int pivot = nums[left], l = left +1, r = right;
while (l <= r){
if(nums[l] < pivot && nums[r] > pivot)
swap(nums, l, r);
if (nums[r] <= pivot) r--;
if (nums[l] >= pivot) l++;
}
swap(nums, left, r);
return r;
}
public static void swap(int nums[], int left, int right){
int temp = nums[left];
nums[left] = nums[right];
nums[right] = temp;
}