Codeforces 385CBear and Prime Numbers Prime table

At first glance at this topic, I think it may be difficult to see not very understand, but look at the given hint after the idea is very clear

Consider the first sample. Overall, the first sample has 3 queries. The first query L = 2, R = comes. You need to count F (2) + F (3) + F (5) + F (7) + f (one) = 2 + 1 + 4 + 2 + 0 = 9.The Second query comes L = 3, R = 12. You need to count F (3) + F (5) + F (7) + f (one) = 1 + 4 + 2 + 0 = 7.The Third query comes L = 4, R = 4. As this interval have no prime numbers, then the sum equals 0.

The range of Xn is in (2≤ x_{i ≤10^{7), while L, R is in the range (2≤ li ≤ ri ≤2 109), easy to calculate the time is not consideredafter 7}}

First of all write a prime number quickly hit the table, but also statistics on the L, the R range of each number to meet the problem conditions of the total (although it seems that the table method is really slow)

Then notice, because the number of queries, up to 5 * 104 times, so at the time of the statistics can calculate the cumulative and to save time

Source Code:

//#pragma COMMENT (linker, "/stack:16777216")//For C + + Compiler#include <stdio.h>#include<iostream>#include<fstream>#include<cstring>#include<cmath>#include<stack>#include<string>#include<map>#include<Set>#include<list>#include<queue>#include<vector>#include<algorithm>#defineMax (b) ((a) > (b))? (a): (b))#defineMin (b) ((a) < (a))? (a): (b))#defineAbs (x) (((x) > 0)? (x): (-(x)))#defineMOD 1000000007#definePi ACOs (-1.0)using namespaceStd;typedefLong Longll; typedef unsignedLong Longull; typedef unsignedint        UINT; typedef unsignedCharUchar; template<classT> InlinevoidCheckmin (T &a,t b) {if(a>b) a=b;} Template<classT> InlinevoidCheckmax (T &a,t b) {if(a<b) a=b;}Const DoubleEPS = 1e-7      ;Const intN = About            ;Const intM =1100011*2      ;Constll P =10000000097ll;Const intMAXN =10900000    ;intCNT[MAXN],A[MAXN];BOOLCHECK[MAXN];voidInit_prime () { for(inti =2; i < MAXN; ++i) {//Prime number playing table        if(!Check[i]) {             for(intj = i; J < Maxn; J + =i) {Check[j]=true; Cnt[i]+=A[j]; }        }    }}intMain () {Std::ios::sync_with_stdio (false); intI, J, T, K, U, V, numcase =0; intN, q, x, y; CIN>>N;  for(i =1; I <= N; ++i) {cin>>x; ++A[x];    } init_prime ();  for(i =2; i < MAXN; ++i) {Cnt[i]+ = Cnt[i-1];//accumulate and save time to query} cin>>T;  while(t--) {cin>> x >>y; Checkmin (x,10000000); Checkmin (Y,10000000); cout<< Cnt[y]-cnt[x-1] <<Endl; }    return 0;}

Codeforces 385CBear and Prime Numbers Prime table