2
3 {
4
5 int ret = 0;
6
7 int len = strlen(x);
8
9 for (int i = 0; i < len; i++)
10
11 {
12
13 if (x[i]-'0' >= b) return -1;
14
15 ret *= b;
16
17 ret += x[i]-'0' ;
18
19 }
20
21 return (long)ret;
22
23 }
24
25 榪欑綆楁硶鍙互灝嗕換鎰忕殑涓涓猙榪涘埗鏁拌漿鍖栨垚10榪涘埗銆?/span>
]]>
2 #include<cmath>
3 #include<iomanip>
4 using namespace std;
5 void sort(double a[],int n)
6 {
7
8 double temp;
9
10 int p,q;
11
12 for(p=1;p<n;p++)
13
14 for(q=p+1;q<=n;q++)
15
16 if(a[p]<a[q])
17
18 {
19
20 temp=a[q];
21
22 a[q]=a[p];
23
24 a[p]=temp;
25
26 }
27
28 }
29
30 int main()
31
32 {
33
34 double i[102],key=1;
35
36 int j,k;
37
38 cin>>k;
39
40 for(j=1;j<=k;j++)
41
42 cin>>i[j];
43
44 if(k==1)
45 cout<<fixed<<setprecision(3)<<i[1]<<endl;
46
47 else
48
49 {
50
51 sort(i,k);
52
53 key=2*sqrt(i[1]*i[2]);
54
55 for(j=3;j<=k;j++)
56
57 key=2*sqrt(key*i[j]);
58
59 cout<<fixed<<setprecision(3)<<key<<endl;
60
61 }
62
63 }
64
65
]]>
鑻ユ鏁存暟n鍙垎瑙ｄ負p1^a1*p1^a2*...*pk^ak
鍏朵腑pi涓轟袱涓や笉鍚岀殑绱犳暟,ai涓哄搴旀寚鏁?br style="PADDING-BOTTOM: 0px; MARGIN: 0px; PADDING-LEFT: 0px; PADDING-RIGHT: 0px; PADDING-TOP: 0px" mce_style="padding: 0px; margin: 0px;"> n鐨勭害鏁頒釜鏁頒負(1+a1)*(1+a2)*....*(1+ak)
濡?80=2*2*3*3*5=2^2*3^2*5
180鐨勭害鏁頒釜鏁頒負(1+2)*(1+2)*(1+1)=18涓?/span>
鑻ユ眰A/B鐨勭害鏁頒釜鏁幫紝A鍙垎瑙ｄ負p1^a1*p2^a2*...*pk^ak錛孊鍙垎瑙ｄ負q1^b1*q1^b2*...*qk^bk,鍒橝/B鐨勭害鏁頒釜鏁? 涓?a1-b1+1)*(a2-b2+1)*(a3-b3+1)...*(ak-bk+1).
鐒跺悗璇碞鐨勯樁涔橈細
渚嬪:20!
1.鍏堟眰鍑?0浠ュ唴鐨勭礌鏁?(2,3,5,7,11,13,17,19)
2.鍐嶆眰鍚勪釜绱犳暟鐨勯樁鏁?br>e(2)=[20/2]+[20/4]+[20/8]+[20/16]=18;
e(3)=[20/3]+[20/9]=8;
e(5)=[20/5]=4;
...
e(19)=[20/19]=1;
鎵浠?br>20!=2^18*3^8*5^4*...*19^1
瑙ｉ噴錛?br>2銆?銆?銆?銆?0銆?2銆?4銆?6銆?8銆?0鑳借2鏁撮櫎
4銆?銆?2銆?6銆?0鑳借4鏁撮櫎錛堝嵆琚?闄や竴嬈″悗榪樿兘琚?鏁撮櫎錛?br>8銆?6鑳借8鏁撮櫎錛堝嵆琚?闄や袱嬈″悗榪樿兘琚?鏁撮櫎錛?br>16鑳借16鏁撮櫎錛堝嵆琚?闄や笁嬈″悗榪樿兘琚?鏁撮櫎錛?br>榪欐牱灝卞緱鍒頒簡2鐨勯樁銆傚叾瀹冨彲浠ヤ緷嬈￠掓帹銆?/span>
鎵浠ュ湪姹侼鐨勯樁涔樿川鏁板洜鏁頒釜鏁版椂錛屼粠鏈灝忕殑璐ㄦ暟寮濮嬶紝
int cal(int n, int p) 
{2
if(n < p) return 0;3
else return n / p + cal(n / p, p);4
}鍏朵腑P鏄川鏁幫紝鍒欒鍑芥暟榪斿洖鐨勫氨鏄疦鐨勯樁涔樹腑鍙互琛ㄨ揪鎴愯川鏁癙鐨勬寚鏁扮殑鏈澶у箋傚師鐞嗗涓娿?/font>
涓嬮潰闄勪笂TOJ 2308鐨凙C浠ｇ爜錛?/span>
#include<iostream>#include<cmath>using namespace std;#define N 90#define M 450 int p[M+2]={0};int prime[N+2],l,q,t=1; //姹傚墠90涓礌鏁?/span>void getprime(int n){ for(l=2;l<n;l++)
{ if(!p[l]) { for(q=l+l;q<n;q+=l) { p[q]=1;
} prime[t]=l;t++; } }}int cal(int n,int m) //姹侼鐨勯樁涔樺惈璐ㄥ洜鏁癕鐨勬鏁?/span>{ if(m>n) return 0; else return n/m+cal(n/m,m);}int main(){ int i,j,k,n; long long m; getprime(M); while(cin>>n>>k) { if(2*k>n) k=n-k; for(i=1,m=1;prime[i]<=n,i<t;i++) m*=(cal(n,prime[i])-cal(k,prime[i])- cal(n-k,prime[i])+1); cout<<m<<endl; }}]]>