归并排序模板

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#include <iostream>
using namespace std;
const int N = 1e6 + 10;
int q[N];
int tmp[N];
void merge_sort(int q[], int l, int r) {
    if(l>=r) return;
    int mid = l + r >> 1;
    merge_sort(q, l, mid);
    merge_sort(q, mid+1, r);

    int k=0, i=l, j=mid+1;
    while(i<=mid && j<=r) {
        if(q[i]<=q[j]) tmp[k++] = q[i++];
        else tmp[k++] = q[j++];
    }
    while(i<=mid) tmp[k++] = q[i++];
    while(j<=r) tmp[k++] = q[j++];
    for(i=l, j=0;i<=r;i++,j++) q[i] = tmp[j];
}
int main() {
    int n;
    scanf("%d", &n);
    for(int i=0;i<n;i++) scanf("%d", &q[i]);
    merge_sort(q, 0, n-1);
    for(int i=0;i<n;i++) printf("%d ", q[i]);
    return 0;
}