题目描述
归并排序
C++ 代码
#include<iostream>
using namespace std;
const int N = 100010;
int tmp[N];
void merge_sort(int q[], int l, int r)
{
if (l >= r) return;
int mid = l + r >> 1;
merge_sort(q, l, mid);
merge_sort(q, mid + 1, r);
int i = l, j = mid + 1, k = 0;
while(i <= mid && j <= r)
{
if(q[i] < q[j]) tmp[k ++] = q[i ++];//这里< , <= 都可以;
else tmp[k ++] = q[j ++];
}
while (i <= mid) tmp[k ++] = q[i ++];//这里是<=;
while (j <= r) tmp[k ++] = q[j ++];
for(i = l, k = 0; i <= r; i ++, k ++) q[i] = tmp[k];//最后要放回去;
}
int main()
{
int n;
scanf("%d", &n);
int q[N];
for(int i = 0; i < n; i ++) scanf("%d", &q[i]);
merge_sort(q, 0, n - 1);
for (int i = 0; i < n; i ++) printf("%d ", q[i]);
return 0;
}