基数排序

= = 现在才会写，感觉有点怂

就是一位一位的比较，对于每一位，使用计数排序，然后排序就好了，而且显然这是一种稳定排序算法。

#include <cstdio>
#include <algorithm>

using namespace std;
const int maxn = 1005;
int num[maxn], n, bid[maxn], cnt[maxn];

int main() {
	while (scanf("%d", &n) != EOF) {
		for (int i = 0; i < n; i++) scanf("%d", &num[i]);
		//基数排序
		int *x = num, *y = bid;
		for (int k = 0, p = 1; k < 10; k++, p *= 10) {
			for (int i = 0; i < 10; i++) cnt[i] = 0;
			for (int i = 0; i < n; i++) {
				int nowval = x[i] % (p * 10) / p;
				cnt[nowval]++;
			}
			for (int i = 1; i < 10; i++) cnt[i] += cnt[i - 1];
			for (int i = n - 1; i >= 0; i--) {
				int nowval = x[i] % (p * 10) / p;
				y[--cnt[nowval]] = x[i];
			}
			int *t; t = x, x = y, y = t;
			for (int i = 0; i < n; i++) printf("%d ", x[i]);
			puts("");
		}
		for (int i = 0; i < n; i++) printf("%d ", x[i]);
		putchar('\n');
	}
	return 0;
}