1 #define IOS ios_base::sync_with_stdio(0); cin.tie(0); 2 #include <cstdio>//sprintf islower isupper 3 #include <cstdlib>//malloc exit strcat itoa system("cls") 4 #include <iostream>//pair 5 #include <fstream>//freopen("C:\Users\13606\Desktop\Input.txt","r",stdin); 6 #include <bitset> 7 //#include <map> 8 //#include<unordered_map> 9 #include <vector> 10 #include <stack> 11 #include <set> 12 #include <string.h>//strstr substr strcat 13 #include <string> 14 #include <time.h>// srand(((unsigned)time(NULL))); Seed n=rand()%10 - 0~9; 15 #include <cmath> 16 #include <deque> 17 #include <queue>//priority_queue<int, vector<int>, greater<int> > q;//less 18 #include <vector>//emplace_back 19 //#include <math.h> 20 #include <cassert> 21 #include <iomanip> 22 //#include <windows.h>//reverse(a,a+len);// ~ ! ~ ! floor 23 #include <algorithm>//sort + unique : sz=unique(b+1,b+n+1)-(b+1);+nth_element(first, nth, last, compare) 24 using namespace std;//next_permutation(a+1,a+1+n);//prev_permutation 25 //****************** 26 clock_t __START,__END; 27 double __TOTALTIME; 28 void _MS(){__START=clock();} 29 void _ME(){__END=clock();__TOTALTIME=(double)(__END-__START)/CLOCKS_PER_SEC;cout<<"Time: "<<__TOTALTIME<<" s"<<endl;} 30 //*********************** 31 #define rint register int 32 #define fo(a,b,c) for(rint a=b;a<=c;++a) 33 #define fr(a,b,c) for(rint a=b;a>=c;--a) 34 #define mem(a,b) memset(a,b,sizeof(a)) 35 #define pr printf 36 #define sc scanf 37 #define ls rt<<1 38 #define rs rt<<1|1 39 typedef pair<int,int> PII; 40 typedef vector<int> VI; 41 typedef long long ll; 42 const double E=2.718281828; 43 const double PI=acos(-1.0); 44 const ll INF=(1LL<<60); 45 const int inf=(1<<30); 46 const double ESP=1e-9; 47 const int mod=(int)1e9+7; 48 const int N=(int)3e6+10; 49 50 int prime[N]; 51 ll phi[N]; 52 bool unprime[N]; 53 54 ///O(NloglogN)，推荐 55 void phi_table() 56 { 57 int i, j; 58 for (i = 2; i < N; ++i) 59 if (!phi[i]) 60 for (j = i; j < N; j += i) 61 { 62 if (!phi[j]) phi[j] = j; 63 phi[j] -= phi[j] / i; ///简化后的代码 64 } 65 } 66 67 ///O(N) 68 void linear_phi_table2() 69 { 70 int i, j, k = 0; 71 for (i = 2; i < N; i++) 72 { 73 if (!unprime[i]) ///若i为素数，phi(i)=i-1 74 { 75 prime[k++] = i; 76 phi[i] = i - 1; 77 } 78 for (j = 0; j < k && prime[j] * i < N; j++) 79 { 80 unprime[prime[j] * i] = true; 81 if (i % prime[j]) ///若i和p互素，则phi(i*p) = phi(i) * phi(p) = phi(i) * (p-1) 82 phi[prime[j] * i] = phi[i] * (prime[j] - 1); 83 else 84 { 85 ///此时有i=kp，则 86 ///phi(p*kp) = phi(k*p^2) = p*phi(kp) 87 phi[prime[j] * i] = phi[i] * prime[j]; 88 break; 89 } 90 } 91 } 92 } 93 94 int main() 95 { 96 int a,b; 97 linear_phi_table2(); 98 for(int i=2;i<=3000010;++i) 99 phi[i]+=phi[i-1]; 100 while(~sc("%d%d",&a,&b)) 101 { 102 pr("%lld ",phi[b]-phi[a-1]); 103 } 104 return 0; 105 } 106 107 /**************************************************************************************/