原理
不做赘述，细看下图：
复杂度
时间复杂度：$O(n\log n)$
空间复杂度：$O(n)$
代码
（码风不好看，不喜勿碰）
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| #include <iostream>
using namespace std;
const int MAXN = 100005;
int n;
int a[MAXN], temp[MAXN];
template<typename T>
void merge_sort(T arr, T temp, int l, int r) {
if (l >= r) return;
int mid = (l + r) >> 1;
merge_sort(arr, temp, l, mid);
merge_sort(arr, temp, mid + 1, r);
int i = l, j = mid + 1, k = l;
while (i <= mid && j <= r)
temp[k ++] = arr[i] < arr[j] ? arr[i ++] : arr[j ++];
while (i <= mid)
temp[k ++] = arr[i ++];
while (j <= r)
temp[k ++] = arr[j ++];
for (register int i = l; i <= r; i ++) arr[i] = temp[i];
}
int main() {
cin >> n;
for (int i = 1; i <= n; i ++) cin >> a[i];
merge_sort(a, temp, 1, n);
for (int i = 1; i <= n; i ++) cout << a[i] << " ";
cout << endl;
return 0;
}
|
当然了，你也可以：
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| #include <iostream>
#include <algorithm>
using namespace std;
int main() {
cin >> n;
for (int i = 1; i <= n; i ++) cin >> a[i];
sort(a + 1, a + 1 + n);
for (int i = 1; i <= n; i ++) cout << a[i] << " ";
cout << endl;
return 0;
}
|
测试传送门
https://www.luogu.com.cn/problem/P1177
代码下载
Download
