[USACO08DEC]Patting Heads S
直接倍数筛即可。
时间复杂度 $O(n\ln n)$。
代码:
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   | #include<iostream> #include<cstdio> #include<algorithm> #define ll long long using namespace std;
  const ll N=1e5,M=1e6;
  ll n;
  ll f[M+5],ans[M+5],a[N+5];
  inline ll read() { 	ll ret=0,f=1;char ch=getchar(); 	while(ch<'0'||ch>'9') {if(ch=='-') f=-f;ch=getchar();} 	while(ch>='0'&&ch<='9') {ret=(ret<<3)+(ret<<1)+ch-'0';ch=getchar();} 	return ret*f; }
  void write(ll x) { 	static char buf[22];static ll len=-1; 	if(x>=0) { 		do{buf[++len]=x%10+48;x/=10;}while(x); 	} 	else { 		putchar('-'); 		do{buf[++len]=-(x%10)+48;x/=10;}while(x); 	} 	while(len>=0) putchar(buf[len--]); }
  void writeln(ll x) { 	write(x);putchar('\n'); }
  int main() {
  	n=read();
  	for(ll i=1;i<=n;i++) { 		a[i]=read();f[a[i]]++; 	}
  	for(ll i=1;i<=M;i++) { 		if(f[i]) { 			for(ll j=i;j<=M;j+=i) { 				ans[j]+=f[i]; 			} 			ans[i]-=1; 		} 	}
  	for(ll i=1;i<=n;i++) { 		writeln(ans[a[i]]); 	}
 
  	return 0; }
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