写个三路归并排序的C++代码
时间: 2023-12-23 16:27:24 浏览: 22
```cpp
#include <iostream>
#include <vector>
using namespace std;
void merge(vector<int>& nums, int left, int mid1, int mid2, int right) {
vector<int> temp(right - left + 1);
int i = left, j = mid1, k = mid2, t = 0;
while (i <= mid1 && j <= mid2 && k <= right) {
if (nums[i] <= nums[j] && nums[i] <= nums[k]) {
temp[t++] = nums[i++];
} else if (nums[j] <= nums[i] && nums[j] <= nums[k]) {
temp[t++] = nums[j++];
} else {
temp[t++] = nums[k++];
}
}
while (i <= mid1 && j <= mid2) {
if (nums[i] <= nums[j]) {
temp[t++] = nums[i++];
} else {
temp[t++] = nums[j++];
}
}
while (i <= mid1 && k <= right) {
if (nums[i] <= nums[k]) {
temp[t++] = nums[i++];
} else {
temp[t++] = nums[k++];
}
}
while (j <= mid2 && k <= right) {
if (nums[j] <= nums[k]) {
temp[t++] = nums[j++];
} else {
temp[t++] = nums[k++];
}
}
while (i <= mid1) {
temp[t++] = nums[i++];
}
while (j <= mid2) {
temp[t++] = nums[j++];
}
while (k <= right) {
temp[t++] = nums[k++];
}
for (int p = 0; p < temp.size(); p++) {
nums[left + p] = temp[p];
}
}
void mergeSort(vector<int>& nums, int left, int right) {
if (left >= right) {
return;
}
int mid1 = left + (right - left) / 3;
int mid2 = left + 2 * (right - left) / 3;
mergeSort(nums, left, mid1);
mergeSort(nums, mid1 + 1, mid2);
mergeSort(nums, mid2 + 1, right);
merge(nums, left, mid1, mid2, right);
}
void printArray(vector<int>& nums) {
for (int num : nums) {
cout << num << " ";
}
cout << endl;
}
int main() {
vector<int> nums = {9, 5, 7, 2, 4, 1, 8, 6, 3};
int n = nums.size();
cout << "Original array: ";
printArray(nums);
mergeSort(nums, 0, n - 1);
cout << "Sorted array: ";
printArray(nums);
return 0;
}
```