Codeforces Round #359 (Div. 2) C. Robbers ' watch (violent Dfs)

Title Link: Http://codeforces.com/problemset/problem/686/C

Give you n and M, ask you how many pairs (a, b) meet 0<=a <n and 0 <=b < m and a 7 binary and n-1 7 binary bits are the same and B 7 is the same as the 7 digits of the m-1, and there are different numbers on each bit on the 7 binary of A and B.

Read the topic, it is very simple, first of all to determine whether A and B 7 of the number of digits more than 7, not more than the DFS violence enumeration calculation on it.

1 //#pragma COMMENT (linker, "/stack:102400000, 102400000")2#include <algorithm>3#include <iostream>4#include <cstdlib>5#include <cstring>6#include <cstdio>7#include <vector>8#include <cmath>9#include <ctime>Ten#include <list> One#include <Set> A#include <map> - using namespacestd; -typedefLong LongLL; thetypedef pair <int,int>P; - Const intN = 1e5 +5; - intnum[Ten], N, m, ans; - BOOLvis[Ten]; +  - int Get(intNum[],intLen) { +     intres =0, temp =1; A      for(inti = len; I >=1; --i) { atRes + = Num[len] *temp; -Temp *=7; -     } -     returnRes; - } -  in voidDfsintLen1,intLen2,intDEP) { -     if(DEP = = Len1 +len2) { to         intsum =0, temp =1; +          for(inti = Len1+len2; I >= len1+1; --i) { -Sum + = temp*Num[i]; theTemp *=7; *         } $         if(Sum <m)Panax Notoginsengans++; -         return ; the     } +     Else if(DEP = =len1) { A         intsum =0, temp =1; the          for(inti = len1; I >=1; --i) { +Sum + = temp*Num[i]; -Temp *=7; $         } $         if(Sum >=N) -             return ; -     }   thedep++; -      for(inti =0; I <7; ++i) {Wuyi         if(Vis[i]) the             Continue; -Vis[i] =true; WuNUM[DEP] =i; - dfs (LEN1, len2, DEP); AboutVis[i] =false; $     } -  - } -  A intMain () + { theCIN >> N >>m; -     intCnt1 =0, Cnt2 =0, temp = n-1; $      Do { theTemp/=7; the++cnt1; the} while(temp); thetemp = M-1; -      Do { inTemp/=7; the++Cnt2; the} while(temp); About     if(Cnt1 + Cnt2 >7) { thecout <<0<<Endl; the}Else { theDFS (Cnt1, Cnt2,0); +cout << ans <<Endl; -     } the     return 0;Bayi}

Codeforces Round #359 (Div. 2) C. Robbers ' watch (violent Dfs)