add heapSort mergeSort

Author: ligecarryme

基础算法篇/排序算法.md

@@ -56,3 +56,85 @@ var partition = function(nums, left, right){
 }
 ```
 
+#### 归并排序
+
+```js
+var mergeSort = function (nums, start, end) {
+    if (start < end) {
+        let mid = (start + end) >> 1;
+        mergeSort(nums, start, mid);
+        mergeSort(nums, mid + 1, end);
+        nums = merge(nums, start, mid, end);
+    }
+    return nums;
+}
+
+var merge = function (nums, left, mid, right) {
+    let arr = [];
+    let i = left, j = mid + 1;
+    while (i <= mid && j <= right) {
+        if (nums[i] < nums[j]) {
+            arr.push(nums[i]);
+            i++;
+        } else {
+            arr.push(nums[j]);
+            j++;
+        }
+    }
+    while (i <= mid) {
+        arr.push(nums[i++]);
+    }
+    while (j <= right) {
+        arr.push(nums[j++]);
+    }
+    return arr;
+}
+
+let nums = [2, 3, 5, 9, 4, 6, 8];
+console.log(mergeSort(nums,0,nums.length-1))
+```
+
+#### 堆排序
+
+用数组表示的完美二叉树 complete binary tree
+
+[动画展示](https://www.bilibili.com/video/av18980178/)
+
+```js
+var move = function (nums, low, high) {
+    let i = low, j = 2 * i + 1;
+    let temp = nums[i];
+    while (j <= high) {
+        if (j < high && nums[j] < nums[j + 1]) {
+            j++;
+        }
+        if (temp < nums[j]) {
+            nums[i] = nums[j];
+            i = j;
+            j = 2 * i + 1;
+        } else {
+            break;
+        }
+    }
+    nums[i] = temp;
+}
+
+var heapSort = function (nums) {
+    let i, temp;
+    let n = nums.length - 1;
+    for (i = n >> 1; i >= 0; i--) {
+        move(nums, i, n);
+    }
+    for (i = n; i >= 1; i--) {
+        temp = nums[0];
+        nums[0] = nums[i];
+        nums[i] = temp;
+        move(nums, 0, i - 1);
+    }
+    return nums;
+}
+
+let arr = [2,4,1,5,8,6,7,9]
+console.log(heapSort(arr))
+```
+