题解上写easy的一道题,但是也没写出来。题目很好,考察的非常灵活。
我觉得再好的题解也没有官方的优秀,所以就直接上传送门:http://discuss.codechef.com/questions/6650/chefhck2-editorial
中间有些小细节可以优化。但算法我觉得基本上已经很完美了。
标程里也有很多小亮点:
1.x&-x是求可以整除x的最大2的幂。
2,若k在[2^b-1,2^b]间,并且k=2^k*m,则二分共要b-k次
/* author:jxy lang:C/C++ university:China,Xidian University **If you need to reprint,please indicate the source** */ #include <iostream> #include <cstdio> #include <cstdlib> #include <cmath> #include <vector> #include <algorithm> using namespace std; int n; long long Max=305731144433251701LL; inline int sqr(long long a) { int x=sqrt(a); return x; } inline bool issqr(long long a) { int x=sqr(a); if((long long)x*x==a)return 1; else return 0; } vector<long long> pws; void pre() { long long i; vector<long long> pw3,pw5; pw3.reserve(700000); pw5.reserve(30000); long long t,a,b; bool f=0; for(i=2;;i++) { if(issqr(i))continue; a=(long long)i*i; b=a*i; if(b>Max)break; pw3.push_back(b); if(f)continue; if(i>=3141)f=1; t=Max/a; b*=a; while(b<=t) { pw5.push_back(b); b*=a; } if(b<=Max)pw5.push_back(b); } sort(pw5.begin(),pw5.end()); pws.resize(pw3.size()+pw5.size()); merge(pw3.begin(),pw3.end(),pw5.begin(),pw5.end(),pws.begin())-pws.begin(); pws.erase(unique(pws.begin(),pws.end()),pws.end()); } inline int l2(long long a) { return ceil(log2(a)); } int bin_search(long long x) { long long t=x&-x; if(t==x) return l2(x); return 2*l2(x)-l2(t)-1; } int solve(long long x) { if(x<=1)return 2-x; int y=sqr(x); int is_sqr=issqr(x); int j=(lower_bound(pws.begin(),pws.end(),x)-pws.begin()); if(is_sqr||pws[j]==x) return j-is_sqr+y; else return bin_search(x+1-j-(y-1)); } int main() { pre(); int T; long long x; scanf("%d",&T); while(T--) { scanf("%lld",&x); printf("%d%c",solve(x),T?' ':'\n'); } }