HDU 6134 Battlestation Operational 2017多校8 莫比乌斯反演

#include <iostream>#include <cstdio>#include <cctype>#include <algorithm>#include <cstring>#include <string>#include <cmath>#include <vector>#include <set>#include <stack>#include <sstream>#include <queue>#include <map>#include <functional>#include <bitset>//#include <unordered_map>//#include <unordered_set>using namespace std;#define pb push_back#define mk make_pair#define ll long long#define ull unsigned long long#define pii pair<int, int>#define fi first#define se second#define mid ((l+r)/2)#define ALL(A) A.begin(), A.end()#define rep(i,n) for(int (i)=0;(i)<(int)(n);(i)++)#define repr(i, n) for(int (i)=(int)(n);(i)>=0;(i)--)#define repab(i,a,b) for(int (i)=(int)(a);(i)<=(int)(b);(i)++)#define reprab(i,a,b) for(int (i)=(int)(a);(i)>=(int)(b);(i)--)#define sc(x) scanf("%d", &x)#define pr(x) printf(#x":%d\n", x)#define fastio ios::sync_with_stdio(0), cin.tie(0)#define frein freopen("in.txt", "r", stdin)#define freout freopen("out.txt", "w", stdout)#define freout1 freopen("out1.txt", "w", stdout)#define lson (rt*2+1)#define rson (rt*2+2)#define br puts("")#define PI M_PI#define debug cout<<"???"<<endlconst ll mod = 1e9+7;const int INF = 0x3f3f3f3f;const double eps = 1e-6;template<class T> T gcd(T a, T b){if(!b)return a;return gcd(b,a%b);}const int maxn = 1e6+100;///d[i]表示i的最小质因子的次幂const int MAX = 1e6+100;int noprime[MAX], facnum[MAX], phi[MAX], mob[MAX], p[MAX], pnum, d[MAX];void get_all(){    int pnum = 0;    phi[1] = 1;    mob[1] = 1;    facnum[1] = 1;    for(int i = 2; i < MAX; i++)    {        if(!noprime[i])        {            phi[i] = i - 1;            mob[i] = -1;            p[pnum ++] = i;            facnum[i] = 2;            d[i] = 1;        }        for(int j = 0; j < pnum && i * p[j] < MAX; j++)        {            noprime[i * p[j]] = true;            if(i % p[j] == 0)            {                phi[i * p[j]] = phi[i] * p[j];                mob[i * p[j]] = 0;                facnum[i * p[j]] = facnum[i] / (d[i] + 1) * (d[i] + 2);                d[i * p[j]] = d[i] + 1;                break;            }            phi[i * p[j]] = phi[i] * (p[j] - 1);            mob[i * p[j]] = -mob[i];            facnum[i * p[j]] = facnum[i] * 2;            d[i * p[j]] = 1;        }    }}int h[maxn], g[maxn];void init(){    get_all();    memset(h, 0, sizeof(h));    memset(g, 0, sizeof(g));    for(int i = 1; i < maxn; i++){        g[i] = (1LL*g[i-1]+facnum[i-1]+1)%mod;    }    for(int i = 1; i < maxn; i++){        for(int j = i; j < maxn; j += i){            h[j] = (h[j] += 1LL*g[i]*mob[j/i]+mod)%mod;        }    }    for(int i = 1; i < maxn; i++){        h[i] = (h[i-1]+1LL*h[i])%mod;    }}int main(){    init();    int n;    while(cin >> n){        cout << h[n] << endl;    }    return 0;}