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Copy pathmergeSort.cpp
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68 lines (58 loc) · 1.61 KB
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#include "sorting.hpp"
#include <vector>
void merge(std::vector<int>& arr, int left, int mid, int right, std::vector<stepStruct>& allSteps)
{
int n1 = mid - left + 1;
int n2 = right - mid;
// Create temp vectors
std::vector<int> L(n1), R(n2);
// Copy data to temp vectors L[] and R[]
for (int i = 0; i < n1; i++)
L[i] = arr[left + i];
for (int j = 0; j < n2; j++)
R[j] = arr[mid + 1 + j];
int i = 0, j = 0;
int k = left;
// Merge the temp vectors back
// into arr[left..right]
while (i < n1 && j < n2) {
if (L[i] <= R[j]) {
arr[k] = L[i];
i++;
allSteps.emplace_back(arr, k, left + i);
}
else {
arr[k] = R[j];
j++;
allSteps.emplace_back(arr, k, mid + 1 + j);
}
k++;
}
// Copy the remaining elements of L[],
// if there are any
while (i < n1) {
arr[k] = L[i];
i++;
k++;
allSteps.emplace_back(arr, k, left + i);
}
// Copy the remaining elements of R[],
// if there are any
while (j < n2) {
arr[k] = R[j];
j++;
k++;
allSteps.emplace_back(arr, k, mid + 1 + j);
}
}
// begin is for left index and end is right index
// of the sub-array of arr to be sorted
void mergeSort(std::vector<int>& arr, int left, int right, std::vector<stepStruct>& allSteps)
{
if (left >= right)
return;
int mid = left + (right - left) / 2;
mergeSort(arr, left, mid, allSteps);
mergeSort(arr, mid + 1, right, allSteps);
merge(arr, left, mid, right, allSteps);
}