0915

Author: kevin-y-ma

leetcode/215-findKthLargest.cpp

@@ -0,0 +1,79 @@
+// 方法一
+class Solution {
+    void adjust(vector<int> & nums, int start, int end)
+    {
+        int dad = start;
+        int son = dad * 2 + 1;
+        while (son<=end) {
+            if ((son+1) <= end && nums[son]<nums[son+1])
+                son += 1;
+            if (nums[dad] < nums[son]) {
+                swap(nums[dad], nums[son]);
+                dad = son;
+                son = dad*2+1;
+            } else {
+                return ;
+            }
+        }
+    }
+    
+    void heapify(vector<int> & nums) 
+    {
+        int len = nums.size();
+        for (int i=len/2-1; i>=0; i--) {
+            adjust(nums, i, len-1);
+        }
+        
+    }
+public:
+    int findKthLargest(vector<int>& nums, int k) {
+        int len = nums.size();
+        heapify(nums);
+        
+        for (int i=len-1; i>=(len-k); i--) {
+            swap(nums[0], nums[i]);
+            adjust(nums, 0, i-1);
+        }
+
+        return nums[len-k];
+    }
+};
+
+// 方法二
+class Solution {
+    int part(vector<int> & nums, int low, int high)
+    {
+        int priv = nums[low];
+        while (low<high) {
+            while (low<high && nums[high] >= priv)
+                high--;
+            nums[low] = nums[high];
+            while (low<high && nums[low] <= priv)
+                low++;
+            nums[high] = nums[low];
+        }
+        nums[low] = priv;
+        return low;
+    }
+    
+    int quick_select(vector<int> & nums, int k, int start, int end)
+    {
+   
+        int priv = part(nums, start, end);
+        if (priv == k)
+            return nums[priv];
+        
+        if (priv > k) 
+            return quick_select(nums, k, start, priv-1);
+        else if (priv < k) 
+            return quick_select(nums, k, priv+1, end);
+        return -1;
+    }
+    
+public:
+    int findKthLargest(vector<int>& nums, int k) {
+        int len = nums.size();
+        return quick_select(nums, len-k, 0, len-1);
+    }
+};
+

sort/README.md

@@ -52,7 +52,7 @@ void SelectSort(ElemType A[]. int n)
 }
 ```
 
-## 堆排序
+## [堆排序](./heap_sort.cpp)
 
 算法思想：   
 
@@ -80,7 +80,7 @@ void BuildMaxHeap(ElemType A[], int len)
 void AdjustDown(ElemType A[], int k, int len)
 {
   A[0] = A[k];
-  for (i=2*k); i<=len; i*=2) {
+  for (i=2*k; i<=len; i*=2) {
     if (i<len && A[i]<A[i+1]) 
       i++;
     if (A[0] >= A[i])
@@ -277,8 +277,8 @@ void MergeSort(ElemType A[], int low, int high)
 | 冒泡排序 |![](http://latex.codecogs.com/gif.latex?O(n)) |![](http://latex.codecogs.com/gif.latex?O(n^2)) | ![](http://latex.codecogs.com/gif.latex?O(n^2)) | ![](http://latex.codecogs.com/gif.latex?O(1)) | 是 |
 |简单选择排序 | ![](http://latex.codecogs.com/gif.latex?O(n^2))  | ![](http://latex.codecogs.com/gif.latex?O(n^2)) | ![](http://latex.codecogs.com/gif.latex?O(n^2)) | ![](http://latex.codecogs.com/gif.latex?O(1)) | 否|
 | 快速排序 | ![](http://latex.codecogs.com/gif.latex?O(nlogn)) |![](http://latex.codecogs.com/gif.latex?O(nlogn)) | ![](http://latex.codecogs.com/gif.latex?O(n^2)) | ![](http://latex.codecogs.com/gif.latex?O(log(n+1))) | 否 |
-| 归并排序 |  ||                      |            |        |
-| 堆排序 |    |            |                      |            |        |
+| 归并排序 | ![](http://latex.codecogs.com/gif.latex?O(nlogn)) |![](http://latex.codecogs.com/gif.latex?O(nlogn))| ![](http://latex.codecogs.com/gif.latex?O(nlogn)) | ![](http://latex.codecogs.com/gif.latex?O(n)) | 是 |
+| 堆排序 | ![](http://latex.codecogs.com/gif.latex?O(nlogn)) | ![](http://latex.codecogs.com/gif.latex?O(nlogn)) | ![](http://latex.codecogs.com/gif.latex?O(nlogn)) | ![](http://latex.codecogs.com/gif.latex?O(n)) | 否 |
 | 桶排序 |    |            |                      |            |        |
 
 

sort/heap_sort.cpp

@@ -0,0 +1,50 @@
+#include <iostream>
+
+using namespace std;
+
+void adjust_down(int * nums, int start, int end)
+{
+	int dad = start;
+	int son = dad*2+1;
+	while (son <= end) {
+		if (son+1 <= end &&  nums[son]<=nums[son+1])
+			son++;
+		if (nums[dad] > nums[son])
+			return ;
+		else {
+			swap(nums[dad], nums[son]);
+			dad = son;
+			son = dad*2+1;
+		}
+	}
+}
+
+void build_max_heap(int * nums, int len)
+{
+	for (int i=len/2-1; i>=0; i--) {
+		adjust_down(nums, i, len-1);
+	}
+}
+
+void heap_sort(int * nums, int len)
+{
+	build_max_heap(nums, len);
+	for (int i=len-1; i>=0; i--) {
+		swap(nums[0], nums[i]);
+		adjust_down(nums, 0, i-1);
+	}	
+}
+
+int main()
+{
+	int nums[] = {7,6,5,4,3,2,1,1,0};
+	//int nums[] = {0,0,1,1,2,3,4,5,6,7};
+
+	heap_sort(nums, sizeof(nums)/sizeof(int));
+
+	for (int i=0; i<sizeof(nums)/sizeof(int); i++)
+		cout<<nums[i]<<" ";
+	cout<<endl;
+
+	return 0;
+}