#include <cstdio>

const int N = 2.5e6 + 20, M = 2e4 + 7;

int n, m;
char c;

void in(int &x)
{
	c = getchar();
	while(c > '9' || c < '0') c = getchar();
	for(x = 0; c >= '0' && c <= '9'; c = getchar())
		x = x * 10 + c - '0';
}

int Hash(int x)
{
	return ((x ^ 1188281) + (x & 12214514)) % M;
}

int h[M + 20];

int main()
{
	in(n); in(m);
	if(m == 1)
	{
		puts("Yes"); return 0;
	}
	int x;
	while(n --)
	{
		in(x); x = Hash(x); x = (x % M + M) % M;
		h[x] ++;
	}
	int i = 0;
	while(i < M)
		if(h[i] % m){puts("No"); return 0;}
		else i ++;
	puts("Yes");
	return 0;
}

答辩题

这个题的空间限制非常紧，只能哈希做

#include <cstdio>

const int N = 2.5e6 + 20, M = 2e4 + 7;

int n, m;
char c;

void in(int &x)
{
	c = getchar();
	while(c > '9' || c < '0') c = getchar();
	for(x = 0; c >= '0' && c <= '9'; c = getchar())
		x = x * 10 + c - '0';
}

int Hash(int x)
{
	return ((x ^ 1188281) + (x & 12214514)) % M;
}

int h[M + 20];

int main()
{
	in(n); in(m);
	if(m == 1)
	{
		puts("Yes"); return 0;
	}
	int x;
	while(n --)
	{
		in(x); x = Hash(x); x = (x % M + M) % M;
		h[x] ++;
	}
	int i = 0;
	while(i < M)
		if(h[i] % m){puts("No"); return 0;}
		else i ++;
	puts("Yes");
	return 0;
}