UvaLive7362 Fare（欧拉函数）

题意：求1~n的素因子之和。

分析：欧拉函数

#include<cstdio>
#include<cstring>
#include<cctype>
#include<cstdlib>
#include<cmath>
#include<iostream>
#include<sstream>
#include<iterator>
#include<algorithm>
#include<string>
#include<vector>
#include<set>
#include<map>
#include<deque>
#include<queue>
#include<stack>
#include<list>
#define fin freopen("in.txt", "r", stdin)
#define fout freopen("out.txt", "w", stdout)
#define pr(x) cout << #x << " : " << x << "   "
#define prln(x) cout << #x << " : " << x << endl
typedef long long ll;
typedef unsigned long long llu;
const int INT_INF = 0x3f3f3f3f;
const int INT_M_INF = 0x7f7f7f7f;
const ll LL_INF = 0x3f3f3f3f3f3f3f3f;
const ll LL_M_INF = 0x7f7f7f7f7f7f7f7f;
const double pi = acos(-1.0);
const double EPS = 1e-6;
const int dx[] = {0, 0, -1, 1};
const int dy[] = {-1, 1, 0, 0};
const ll MOD = 1e9 + 7;
const int MAXN = 10000 + 10;
const int MAXT = 10000 + 10;
using namespace std;
int pr[MAXN];
int ps[MAXN];
void init()
{
    for(int i = 2; i <= 10000; ++i)
    {
        int tmp1 = i;
        int tmp2 = i;
        for(int j = 2; j <= i; ++j)
            if(tmp2 % j == 0)
            {
                tmp1 = tmp1 / j * (j - 1);
                tmp2 /= j;
                while(!(tmp2 % j))
                    tmp2 /= j;
            }
        pr[i] = tmp1;
    }
    ps[1] = 2;
    for(int i = 2; i <= 10000; ++i)
        ps[i] = ps[i - 1] + pr[i];
}
int main()
{
    int P;
    scanf("%d", &P);
    init();
    while(P--)
    {
        int x, n;
        scanf("%d%d", &x, &n);
        printf("%d %d\n", x, ps[n]);
    }
    return 0;
}