MergeSort C++实现

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MergeSort的C++实现，时间复杂度为O(nlogn)，空间复杂度为O(n)

#include <iostream>using namespace std;void Merge(int arr[], int start, int mid, int end) {int LeftLen = mid - start + 1;int RightLen = end - mid;int* Left = new int[LeftLen];int* Right = new int[RightLen];int i = 0, j = 0, k = 0, f = 0;for (i = 0,k = start; i < LeftLen; i++, k++) {Left[i] = arr[k];}for (i = 0, k = mid+1; i < RightLen; i++, k++) {Right[i] = arr[k];}for (k = start, i = 0, j = 0; i < LeftLen & j < RightLen; k++) {if (Left[i] <= Right[j]) {arr[k] = Left[i];i++;}if (Left[i] > Right[j]) {arr[k] = Right[j];j++;}}if (i < LeftLen) {for (f = i; f < LeftLen; f++, k++) {arr[k] = Left[f];}}if (j < RightLen) {for (f = j; f < RightLen; f++,k++) {arr[k] = Right[f];}}}void MergeSort(int arr[], int start, int end) {if (start < end) {int mid = (start+end)/2;MergeSort(arr,start, mid);MergeSort(arr,mid+1, end);Merge(arr, start, mid, end);}}int main() {  int x;  cin >> x;  int arr[x];  for(int i = 0; i < x; i++) {  cin >> arr[i];  }  MergeSort(arr, 0, x-1);  for (int i = 0; i < x; i++) {  cout << arr[i] << " ";  }  cout << endl;   return 0;  }

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