归并排序
C语言代码
#include <stdlib.h>
#include <stdio.h>
void Merge(int sourceArr[],int tempArr[], int startIndex, int midIndex, int endIndex)
{
int i = startIndex, j=midIndex+1, k = startIndex;
while(i!=midIndex+1 && j!=endIndex+1)
{
if(sourceArr[i] > sourceArr[j])
tempArr[k++] = sourceArr[j++];
else
tempArr[k++] = sourceArr[i++];
}
while(i != midIndex+1)
tempArr[k++] = sourceArr[i++];
while(j != endIndex+1)
tempArr[k++] = sourceArr[j++];
for(i=startIndex; i<=endIndex; i++)
sourceArr[i] = tempArr[i];
}
//内部使用递归
void MergeSort(int sourceArr[], int tempArr[], int startIndex, int endIndex)
{
int midIndex;
if(startIndex < endIndex)
{
midIndex = startIndex + (endIndex-startIndex) / 2;//避免溢出int
MergeSort(sourceArr, tempArr, startIndex, midIndex);
MergeSort(sourceArr, tempArr, midIndex+1, endIndex);
Merge(sourceArr, tempArr, startIndex, midIndex, endIndex);
}
}
int main(int argc, char * argv[])
{
int a[8] = {50, 10, 20, 30, 70, 40, 80, 60};
int i, b[8];
MergeSort(a, b, 0, 7);
for(i=0; i<8; i++)
printf("%d ", a[i]);
printf("\n");
return 0;
}
C++代码
#include<iostream>
using namespace std;
void merge(int a[],int l,int r,int mid){
int b[r-l+1];
//b[0,mid] b[mid+1,r]
int i,j,k;
for(i=l;i<=r;i++)
b[i-l]=a[i];
i=l;
j=mid+1;
for(k=l;k<=r;k++){
if(i>mid){
a[k]=b[j-l];
j++;
}
else if(j>r){
a[k]=b[i-l];
i++;
}
else if(b[i-l]>b[j-l]){
a[k]=b[j-l];
j++;
}
else{
a[k]=b[i-l];
i++;
}
}
}
void merge_sort(int a[],int l,int r){
if(l>=r)
return ;
int mid=(l+r)/2;
merge_sort(a,l,mid);
merge_sort(a,mid+1,r);
merge(a,l,r,mid);
}
int main(){
int a[10]={3,2,4,8,1,9,0,5,7,6};
merge_sort(a,0,9);
for(int i=0;i<10;i++)
cout<<a[i]<<' ';
return 0;
}
理解
归并流程
合并两个有序数组