归并排序

归并排序

很久没打了，现在发现思路跟线段树差不多

#include <bits/stdc++.h>
using namespace std;

const int MAXN = (int) 1e6+7;

int N;
int A  [MAXN];
int Tmp[MAXN];

void Merge(int l,int r){
    if (l == r) {
        Tmp[l] = A[l];
        return ;
    }

    int m = (l+r)>>1;
    Merge(l,m);
    Merge(m+1,r);

    int i = l,j = m+1;
    int t = l;
    while (i <= m && j <= r){
        if (Tmp[i] < Tmp[j]){
            A[t++] = Tmp[i++];
        }else {
            A[t++] = Tmp[j++];
        }
    }
    while (i <= m) A[t++] = Tmp[i++];
    while (j <= r) A[t++] = Tmp[j++];

    for (int i = l;i <= r;i ++)Tmp[i] = A[i];
}

int main()
{
    scanf("%d",&N);
    for (int i = 1;i <= N;i ++) scanf("%d",&A[i]);
    Merge(1,N);
    for (int i = 1;i <= N;i ++) printf("%d%c",A[i],i==N?'\n':' ');
}