A. Division 【数学】1500
A. Division
题意 给定p和q,找一个最大的x,x能整除p,但是q不能整除x
分析
x肯定是p的唯一分解定理的一部分,所以可以考虑从x中删除一下,使得q整除x。由于p太大,分解它肯定会超时,所以可以分解q,然后看q的每一个质因数的次方,p的这个质因数次方是否都小于它。如果都小于它,那么答案就是p,否则就让某个质数的次方,让p这边小于q(这里暴力一下就行)
代码
#include <bits/stdc++.h> #define ios ios_base::sync_with_stdio(0),cin.tie(0),cout.tie(0) #define debug_in freopen("in.txt","r",stdin) #define debug_out freopen("out.txt","w",stdout); #define pb push_back #define all(x) x.begin(),x.end() #define fs first #define sc second using namespace std; typedef long long ll; typedef unsigned long long ull; typedef pair<ll,ll> pii; const ll maxn = 1e6+10; const ll maxM = 1e6+10; const ll inf = 1e8; const ll inf2 = 1e17; template<class T>void read(T &x){ T s=0,w=1; char ch=getchar(); while(ch<'0'||ch>'9'){if(ch=='-')w=-1;ch=getchar();} while(ch>='0'&&ch<='9') s=s*10+ch-'0',ch=getchar(); x = s*w; } template<class H, class... T> void read(H& h, T&... t) { read(h); read(t...); } void pt(){ cout<<'\n';} template<class H, class ... T> void pt(H h,T... t){ cout<<" "<<h; pt(t...);} //-------------------------------------------- int T; ll a,b; int P[maxn],tail; bool vis[maxn]; map<int,int> mp; ll A,B; void initP(int N){ vis[1] = 1; for(int i = 2;i<=N;i++){ if(!vis[i]) P[tail++] = i; for(int j = 0;j<tail && P[j] <= N/i;j++){ vis[P[j] * i] = 1; if(i % P[j] == 0) break; } } } ll ksm(ll a,ll b){ ll res = 1; while(b){ if(b&1) res = res * a; b>>=1; a*=a; } return res; } void solve(){ read(A,B); ll a = A,b = B; mp.clear(); for(int i = 0;i<tail && P[i] * P[i]<=b;i++){ if(b % P[i] == 0){ int cnt = 0; while(b % P[i] == 0){ cnt ++; b/=P[i]; } mp[P[i]] = cnt; } } if(b > 1) mp[b] = 1; int find = 0; for(auto pp:mp){ ll p = pp.fs,cnt = pp.sc; ll coun = 0,a = A; while(a%p == 0){ coun++; a/=p; } if(coun < cnt){ find = 1; break; } } if(find){ printf("%lld\n",A); }else{ ll ans = 0; for(auto pp:mp){ ll p = pp.fs,cnt = pp.sc; ll coun = 0,a = A; while(a%p == 0){ coun++; a/=p; } if(coun >= cnt){ ans = max(ans,A/ksm(p,coun - cnt + 1)); } } printf("%lld\n",ans); } } int main(){ // debug_in; initP(1000000); read(T); while(T--){ solve(); } return 0; }
Ryuichi的算法分享 文章被收录于专栏
分享我的一些算法题解,致力于把题解做好,部分题解可能会采用视频的形式来讲解。