归并排序

#include<iostream>
using namespace std;
#include<queue>
#include<cstdio>
#include<cstdlib>
const int maxn = 1e2+1;
int arr[maxn];
int temp[maxn];

void merge(int beg, int mid, int end){
	int i = beg, j = mid+1;
	int t = 0;
	while(i <= mid && j <= end){
		if(arr[i] <= arr[j]){
			temp[t++] = arr[i++];
		}
		else{
			temp[t++] = arr[j++];
		}
	}
	while(i <= mid){
		temp[t++] = arr[i++];
	}
	while(j <= end){
		temp[t++] = arr[j++];
	}
	//复制 
	for(int i = 0; i < t; i++) arr[beg+i] = temp[i];
}

void mergeSort(int beg, int end){
	if(beg < end){
		int mid = (beg+end) / 2;
		mergeSort(beg, mid);
		mergeSort(mid+1, end); 
		merge(beg, mid, end);
	}
}

int main(){
	//freopen("in.txt", "r", stdin);
	int n;
	cin >> n; 
	for(int i = 0; i < n; i++){
		scanf("%d", &arr[i]);
	}
	
	for(int i = 0; i < n; i++){
		printf("%d ", arr[i]);
	}
	cout << endl;
	
	mergeSort(0,n-1);
	
	for(int i = 0; i < n; i++){
		printf("%d ", arr[i]);
	}
	
	return 0;
}