标签：dad https not length 堆排序 步骤 之间 ret cpp
题目来源：https://leetcode.com/problems/kth-largest-element-in-an-array/description/
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.
For example,
Given [3,2,1,5,6,4] and k = 2, return 5.
Note:
You may assume k is always valid, 1 ≤ k ≤ array‘s length.
class Solution {
void heapFixDown(vector<int>& arr, int start, int end) {
int dad = start;
int son = dad * 2 + 1;
while (son <= end) {
if (son + 1 <= end && arr[son] < arr[son + 1])
son++;
if (arr[dad] >= arr[son]) {
return;
} else {
swap(arr[dad], arr[son]);
dad = son;
son = dad * 2 + 1;
}
}
}
void makeHeap(vector<int>& arr, int len) {
for (int i = len / 2 - 1; i >= 0; i--) {
heapFixDown(arr, i, len - 1);
// printArr(arr, len);
}
// cout << "finish makeHeap" << endl;
}
void heapSort(vector<int>& arr, int len) {
makeHeap(arr, len);
for (int i = len - 1; i >= 1; i--) {
swap(arr[i], arr[0]);
heapFixDown(arr, 0, i - 1);
// printArr(arr, len);
}
}
public:
int findKthLargest(vector<int>& nums, int k) {
int len = nums.size();
heapSort(nums, len);
return nums[len - k];
}
};这道题我的基本思路是先对数组进行排序然后再直接获得K大的元素。排序部分使用了堆排序。
堆排序的关键步骤包含：
[Leetcode Week11]Kth Largest Element in an Array
标签：dad https not length 堆排序 步骤 之间 ret cpp
原文地址：http://www.cnblogs.com/yanhewu/p/7857469.html
