「算法导论」：归并排序

/*************************************************************************
> File Name: merge_sort.cpp
> Author sangoly
> Mail: sangoly@aliyun.com
> Created Time: 2014年06月30日 星期一 20时32分44秒
************************************************************************/

#include<iostream>
#include<limits>
using namespace std;

void merge(int list[], int start, int middle, int end) {
int llen = middle - start + 1;
int rlen = end - middle;

int* larr = new int[llen + 1];
int* rarr = new int[rlen + 1];

int i, j;
for (i = 0; i < llen; i++) {
larr[i] = list[start + i];
}
for (j = 0; j < rlen; j++) {
rarr[j] = list[middle + 1 + j];
}
// Add the guard
larr[llen] = numeric_limits<int>::max();
rarr[rlen] = numeric_limits<int>::max();

i = j = 0;
for (int k = start; k <= end; k++) {
if (larr[i] <= rarr[j])
list[k] = larr[i++];
else
list[k] = rarr[j++];
}
delete [] larr;
delete [] rarr;
}

void merge_sort(int list[], int start, int end) {
if (start >= end)
return;
int middle = (start + end) / 2;
merge_sort(list, start, middle);
merge_sort(list, middle + 1, end);
merge(list, start, middle, end);
}

int main() {
int list[8] = {5, 10, 4, 7, 1, 15, 2, 6};
merge_sort(list, 0, 7);
for (int i = 0; i < 8; i++)
cout<<list[i]<<" ";
cout<<endl;
return 0;
}