归并排序

Posted 2021-03-22 buaazhhx

#include<iostream>
#include<cstring>
#include<vector>
#include<algorithm>
#include<map>


using namespace std;


void merge(int A[], int left,int mid,int right){
   int p1 = left;
   int p2 = mid + 1;
   int temp[right-left+1];
   int i = 0;
   while(p1 <= mid && p2 <= right){
        temp[i++] = A[p1] > A[p2] ? A[p2++] : A[p1++];
   }
   while(p1 <= mid){
        temp[i++] = A[p1++];
   }
   while(p2 <= right){
        temp[i++] = A[p2++];
   }

   for(int i = left; i <= right; i++){
        A[i] = temp[i-left];
   }
}
void sort(int A[], int left,int right) {
    if(left == right){
       return;
    }
    int mid = left + ((right-left) >> 2);
    sort(A,left,mid);
    sort(A,mid+1,right);
    merge(A,left,mid,right);
}

int main(){
    int a[] = {5,4,7,9,3,8,2,1};
    sort(a,0,8);
    for(int i = 0; i < 8;i++){
        cout<<a[i]<<" ";
    }
    return 0;
}