C++语言-外部排序算法-二路归并排序

二路归并排序，时间复杂度O(nlogn)

#include <iostream>
#include <vector>
using namespace std;vector<int> b(1000, 0);void Merge(vector<int>& a, int low, int mid, int high) {for (int i = low; i <= high; ++i) {b[i] = a[i];}int t = low;int i = low;int j = mid+1;while (i <= mid && j <= high) {if (b[i] <= b[j]) {a[t++] = b[i++];} else {a[t++] = b[j++];}}while (i <= mid) {a[t++] = b[i++];}while (j <= high) {a[t++] = b[j++];}
}void MergeSort(vector<int>& a, int low, int high) {if (low < high) {int mid = (low + high) / 2;MergeSort(a, low, mid);MergeSort(a, mid+1, high);Merge(a, low, mid, high);}
}int main(int argc, char* argv[]) {vector<int> vec = {2, 1, 5, 3, 5, 4, 12, 11, 8, 10};for (int i = 0; i < vec.size(); ++i) {cout << vec[i] << " ";}cout << endl;MergeSort(vec, 0, vec.size()-1);for (int i = 0; i < vec.size(); ++i) {cout << vec[i] << " ";}cout << endl;return 0;
}