# vijosP1447 Switch Bulb

Source: Internet
Author: User

vijosP1447 Switch Bulb

Ideas

Math + High precision.

Analysis of the topic: in the words, I will be all its multiples of the lights out, so that a number of how many multiples will be operated how many times, because the initial all extinguished, so the operation of the odd lamp will finally light, and further, only the number of squares of the lamp in the end will be lit.

The number of sqrt (n) is converted to the number of squares within n (don't ask me how I know =_=)

Data range requires that we use high-precision. At this point, the topic is to a large number of the problem, Noip in the preliminary round has appeared this program.

Code

`1#include <iostream>2#include <cstring>3#include <cmath>4 using namespacestd;5 6 Const intMAXN = \$+Ten;7 structbign{8     intLen;9     intNUM[MAXN];TenBign () {memset (num,0,sizeof(num)); } One }; A  - bign goal; -  the bign times (bign a,bign b) { - bign C; -c.len=a.len+b.len+2; -      for(intI=0; i<a.len;i++) +        for(intj=0; j<b.len;j++) -C.NUM[I+J] + = a.num[i]*B.num[j]; +      for(intI=0; i<c.len-1; i++) { Ac.num[i+1] + = c.num[i]/Ten; atC.num[i]%=Ten; -     } -      while(c.num[c.len-1]==0) c.len--; -     returnC; - } -  in bign average (bign a,bign b) { -Bign C; c.len=Max (A.len,b.len); to      for(intI=0; i<c.len;i++) { +C.num[i] + = a.num[i]+B.num[i]; -c.num[i+1] + = c.num[i]/Ten; theC.num[i]%=Ten; *     } \$     Panax Notoginseng     if(C.num[c.len]) c.len++; -      for(inti=c.len-1; i;i--) { thec.num[i-1] + = (c.num[i]%2) *Ten; +C.num[i]/=2; A     } thec.num[0]/=2; +     if(c.num[c.len-1]==0) c.len--; -     returnC; \$ } \$  - bign Plustwo (Bign a) { -a.num[0] +=2; the     intI=0; -      while(I<a.len && a.num[i]>=Ten) {Wuyia.num[i+1] + = a.num[i]/Ten; theA.num[i]%=Ten; -i++; Wu     } -     if(A.num[a.len]) a.len++; About     returnA; \$ } -  - BOOLOver (bign a,bign b) { -     if(A.len>b.len)return true; A     Else if(A.len<b.len)return false; +      the      for(inti=a.len;i>=0; i--)//Reverse -       if(A.num[i]>b.num[i])return true; \$       Else if(A.num[i]<b.num[i])return false; the      the     return false; the } the  - intMain () { inIos::sync_with_stdio (false); the     strings; theCin>>s; Aboutgoal.len=s.size (); the      for(intI=0; i<goal.len;i++) goal.num[i]=s[goal.len-1-i]-'0'; theBign L, r=goal, M; thel.len=1; l.num[0]=1; +      Do -      { them=average (l,r);Bayi            if(Over (Times (M,M), goal)) R=M; the            ElseL=M; the} while(!Over (Plustwo (L), R)); -      for(inti=l.len-1; i>=0; i--) cout<<L.num[i]; -     return 0; the}`

vijosP1447 Switch Bulb

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