Ultraviolet A 10539-almost prime numbers (number theory)

Link to the Q & A 10539-almost prime numbers topic

Scope: Low ~ High: the number of records in this range must be n = Pb (P is a prime number ).

Solution: first, the prime number within 1e6 is processed, and then solve (high) is used for each range )? Solve (low? 1), solve (n) is used to process the number of numbers that meet the requirements less than N. Enumerative prime numbers. You can judge them.

#include <cstdio>#include <cstring>typedef long long ll;const int maxn = 1e6;ll lower, up, prime[maxn];int cp, v[maxn];void primeTable (int n) {    cp = 0;    memset(v, 0, sizeof(v));    for (int i = 2; i <= n; i++) {        if (v[i])            continue;        prime[cp++] = i;        for (int j = 2 * i; j <= n; j += i)            v[j] = 1;    }}ll solve (ll n) {    ll ans = 0;    for (int i = 0; i < cp; i++) {        ll u = prime[i] * prime[i];        if (u > n)            break;        while (u <= n) {            u *= prime[i];            ans++;        }    }    return ans;}int main () {    primeTable(maxn);    int cas;    scanf("%d", &cas);    while (cas--) {        scanf("%lld%lld", &lower, &up);        printf("%lld\n", solve(up) - solve(lower-1));    }    return 0;}