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1. 幂的阶乘【分解质因数】

   #include <iostream>
   #include <cstring>
   #include <algorithm>
   #include <cstdio>
   using namespace std;
   const int inf = 0x3f3f3f3f;
   
   int main() {
     int t, n, m, cas = 1;
     scanf("%d", &t);
     while (t--) {
       scanf("%d%d", &m, &n);
       int i = 2;
       int ans = inf;
       while (m != 1) {
         int p = 0;
         while (m % i == 0) {
           m /= i;
           p++;
         }
         if (p) {
           int num = n;
           int tmp = 0;
           while (num) {
             tmp += num/i;
             num /= i;
           }
           ans = min(ans, tmp/p);
         }
         i++;
       }
       printf("Case %d:\n", cas++);
       if (ans)
         printf("%d\n", ans);
       else printf("Impossible to divide\n");
     }
     return 0;
   }

2. 排列之和【】

#include <iostream>
#include <cstring>
#include <cstdio>
#include <algorithm>
typedef unsigned long long ll;
using namespace std;
const int maxn = 20;

int num[maxn], f[maxn];
int n;

void init() {
	f[0] = f[1] = 1;
	for (int i = 2; i < maxn; i++)
		f[i] = f[i-1] * i;
}

ll cal(int x) {
	ll tmp = 1;
	for (int i = 0; i < 10; i++)
		if (i == x)
			tmp *= f[num[i]-1];
		else tmp *= f[num[i]];
	return (ll)(f[n-1]) / tmp;
}

int main() {
	int a;
	init();
	while (scanf("%d", &n) != EOF && n) {
		memset(num, 0, sizeof(num));
		for (int i = 0; i < n; i++) {
			scanf("%d", &a);
			num[a]++;
		}
		ll sum = 0;
		for (int i = 0; i < 10; i++)
			if (num[i])
				sum += (ll)(i) * cal(i);
		ll ans = 0;
		for (int i = 0; i < n; i++)
			ans = ans * 10 + sum;
		printf("%lld\n", ans);
	}
	return 0;
}