StrangeStandard
Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 70 Accepted Submission(s): 31
Problem Description
Nowadays, WHUACMer use a strange standard to evaluate a natural number.The evaluating value of a natural number is the amount of it’s divisors.If a number m has bigger evaluating value than all the numbers smaller than it, we call it a good number. Now give you a number n, find the maximum good number which is not bigger than n.
Input
The first line contains a single integer T(T<=10), indicating the number of test cases.
For each test case,there is only one line which only contains one number n(1 <= n <= 2 000 000 000)
For each test case,there is only one line which only contains one number n(1 <= n <= 2 000 000 000)
Output
For each test case,output the case number first,then output the maximum good number which is not bigger than n.
Sample Input
1 1000
Sample Output
Case #1: 840
Source
Recommend
lcy
很明显的反素数搜索。
照着模板写就行了。。
我的代码:
#include<stdio.h> __int64 prime[16]={2,3,5,7,11,13,17,19,23,29,31,37,41,43,47}; __int64 n,cnter,ans; void dfs(__int64 cur,__int64 cnt,__int64 power,__int64 sub) { __int64 i; if(cur>n) return; if(cnt==cnter&&cur<ans) ans=cur; if(cnt>cnter) { ans=cur; cnter=cnt; } __int64 p=prime[sub]; for(i=1;i<=power;i++) { if(cur*p>n) break; dfs(cur*p,cnt*(i+1),i,sub+1); p=p*prime[sub]; } } int main() { int t,T; scanf("%d",&T); for(t=1;t<=T;t++) { scanf("%I64d",&n); cnter=0,ans=0; dfs(1,1,50,0); printf("Case #%d: %I64d\n",t,ans); } return 0; }