C++ 병합정렬 구현

1 개요[ | ]

C++ 병합정렬 구현
#include <iostream>
void merge_sort(int a[], int left, int right) {
    if( left>=right ) return;
    int middle = (left+right-1)/2;
    merge_sort(a, left, middle);
    merge_sort(a, middle+1, right);
    int n1 = middle + 1 - left;
    int n2 = right - middle;
    int i, j, k, L[n1], R[n2];
    for(i=0; i<n1; i++) L[i]=a[left+i];
    for(i=0; i<n2; i++) R[i]=a[middle+1+i];
    i=j=0; k=left;
    while( i<n1 && j<n2 ) {
        if( L[i]<=R[j] ) { a[k]=L[i]; i++; k++; }
        else { a[k]=R[j]; j++; k++; }
    }
    while( i<n1 ) { a[k]=L[i]; i++; k++; }
    while( j<n2 ) { a[k]=R[j]; j++; k++; }
}
int main() {
    int arr[] = {9,1,22,4,0,-1,1,22,100,10};
    int size = sizeof(arr)/sizeof(int);
    merge_sort(arr, 0, size-1);
    for(int x: arr) std::cout << x << " ";
    // -1 0 1 1 4 9 10 22 22 100 
}
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