UVa 294-divisors

Through this problem learned 2 knowledge:

1. The qualitative factor of a number must be less than or equal to the open root of this number

2. The number of factors (approximate) is equal to π (the number of factors +1)

#include <cstdio> #include <cstring> #include <algorithm> #include <cmath>using namespace std; const int MAXN = 55555;//#define Debugint vis[maxn];int prime[maxn];int cnt = 0;void getprime () {memset (vis,0,sizeof (vi    s));    int m = sqrt (MAXN) + 1;    for (int i = 2; l < m; i++) if (!vis[i]) {for (int j = i * i; j < maxn; J + = i) vis[j] = 1;    } for (int i = 2; i < MAXN; i++) if (!vis[i]) prime[cnt++] = i;    #ifdef DEBUG for (int i = 0; i < cnt; i++) printf ("%d", prime[i]);    #endif//Debug}int solve (int n) {int sum = 1;            for (int i = 0; i < CNT && n > 1; i++) {if (n prime[i] = = 0) {int c = 1;                while (n% prime[i] = = 0) {C + +;            n/= Prime[i];        } sum *= C; }} return sum;}    int main () {int n,t;    Getprime ();    scanf ("%d", &t);        while (t--) {int A, B;        scanf ("%d%d", &a,&b); int temp = 0;        int ret;            for (int i = A; I <= b; i++) {int e = solve (i);                if (Temp < e) {temp = e;            ret = i;    }} printf ("Between%d and%d,%d has a maximum of%d divisors.\n", a,b,ret,temp); } return 0;}

UVa 294-divisors