Update 5.mergeSort.md

shouao · web-flow · commit 1f7b01b699f9 · 2022-01-01T07:18:06.000+08:00
diff --git a/5.mergeSort.md b/5.mergeSort.md
@@ -227,34 +227,36 @@ function merge($left, $right)
 ## 9. C++ &#20195;&#30721;&#23454;&#29616;
 
 ```cpp
-void merge(vector<int>& nums, int l, int mid, int r) {
+void merge(vector<int>& arr, int l, int mid, int r) {
     int index = 0;
     int ptrL = l;
     int ptrR = mid;
     static vector<int>tempary;
-    tempary.resize(nums.size());
+    if (arr.size() > tempary.size()) {
+        tempary.resize(arr.size());
+    }
     while (ptrL != mid && ptrR != r) {
-        if (nums[ptrL] < nums[ptrR]) {
-            tempary[index++] = nums[ptrL++];
+        if (arr[ptrL] < arr[ptrR]) {
+            tempary[index++] = arr[ptrL++];
         } else {
-            tempary[index++] = nums[ptrR++];
+            tempary[index++] = arr[ptrR++];
         }
     }
     while (ptrL != mid) {
-        tempary[index++] = nums[ptrL++];
+        tempary[index++] = arr[ptrL++];
     }
     while (ptrR != r) {
-        tempary[index++] = nums[ptrR++];
+        tempary[index++] = arr[ptrR++];
     }
-    copy(tempary.begin(), tempary.begin() + index, nums.begin() + l);
+    copy(tempary.begin(), tempary.begin() + index, arr.begin() + l);
 }
-void mergeSort(vector<int>& nums, int l, int r) {// sort the range [l, r), so if there is a 0-index array arr whose length is n
-    if (r - l <= 1) {                            //and you want sort the whole array, "mergeSort(arr, 0, n)" should be called
+void mergeSort(vector<int>& arr, int l, int r) { // sort the range [l, r) in arr
+    if (r - l <= 1) {
         return;
     }
     int mid = (l + r) / 2;
-    mergeSort(nums, l, mid);
-    mergeSort(nums, mid, r);
-    merge(nums, l, mid, r);
+    mergeSort(arr, l, mid);
+    mergeSort(arr, mid, r);
+    merge(arr, l, mid, r);
 }
 ```
