【数学】 HDOJ 5051 Fraction

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公式题。。。

本福特定律说明在b进位制中，以数n起头的数出现的机率为logb(n + 1) − logb(n) .

#include <iostream>  #include <queue>  #include <stack>  #include <map>  #include <set>  #include <bitset>  #include <cstdio>  #include <algorithm>  #include <cstring>  #include <climits>#include <cstdlib>#include <cmath>#include <time.h>#define maxn 1205#define maxm 40005#define eps 1e-10#define mod 10000007#define INF 1e9#define lowbit(x) (x&(-x))#define mp make_pair#define ls o<<1#define rs o<<1 | 1#define lson o<<1, L, mid  #define rson o<<1 | 1, mid+1, R  typedef long long LL;typedef unsigned long long ULL;//typedef int LL;using namespace std;LL qpow(LL a, LL b){LL res=1,base=a;while(b){if(b%2)res=res*base;base=base*base;b/=2;}return res;}LL powmod(LL a, LL b){LL res=1,base=a;while(b){if(b%2)res=res*base%mod;base=base*base%mod;b/=2;}return res;}void scanf(int &__x){__x=0;char __ch=getchar();while(__ch==' '||__ch=='\n')__ch=getchar();while(__ch>='0'&&__ch<='9')__x=__x*10+__ch-'0',__ch = getchar();}LL gcd(LL _a, LL _b){if(!_b) return _a;else return gcd(_b, _a%_b);}//headint main(void){int _, __, n, q, b;while(scanf("%d", &_)!=EOF) {__ = 0;while(_--) {scanf("%d%d%d", &n, &b, &q);double x = (log(n+1) - log(n))/log(10.0);if(q == 1) {while(b > n) b /= 10;if(b == n) x = 1.0;else x = 0.0;printf("Case #%d: %.5f\n", ++__, x);}else if(q == 10 || q == 100 || q == 1000) {b *= 10000;while(b > n) b /= 10;if(b == n) x = 1.0;else x = 0.0;printf("Case #%d: %.5f\n", ++__, x);}else printf("Case #%d: %.5f\n", ++__, x);}}return 0;}

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