HDU 4135 Co-prime（容斥原理）

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题意：（a，b）间与n互素的个数。

容斥原理裸题。。

ans = b - a + Inclusion_exclusion(0, a - 1) - Inclusion_exclusion(0, b) + 1。

数据有1e15，小心爆int。

代码：

// Header.#include <algorithm>#include <iostream>#include <sstream>#include <cstring>#include <cstdio>#include <vector>#include <string>#include <bitset>#include <queue>#include <stack>#include <cmath>#include <ctime>#include <set>#include <map>using namespace std;// Macrotypedef long long LL;#define TIME cerr << "Time elapsed: " << 1.0 * clock() / CLOCKS_PER_SEC << "s." << endl;#define IN freopen("/Users/apple/input.txt", "r", stdin);#define OUT freopen("/Users/apple/out.txt", "w", stdout);#define mem(a, n) memset(a, n, sizeof(a))#define rep(i, n) for(int i = 0; i < (n); i ++)#define REP(i, t, n) for(int i = (t); i < (n); i ++)#define FOR(i, t, n) for(int i = (t); i <= (n); i ++)#define ALL(v) v.begin(), v.end()#define Min(a, b) a = min(a, b)#define Max(a, b) a = max(a, b)#define put(a) printf("%d\n", a)#define ss(a) scanf("%s", a)#define si(a) scanf("%d", &a)#define sii(a, b) scanf("%d%d", &a, &b)#define siii(a, b, c) scanf("%d%d%d", &a, &b, &c)#define VI vector<int>#define pb push_backconst int inf = 0x3f3f3f3f, N = 1e2 + 5, MOD = 1e9 + 7;// Macro endint T, cas = 0;LL n, m, a, b;vector<LL> prime;// Impvoid prime_init(LL n) {LL m = (LL)sqrt(n + 0.5);for(LL i = 2; i <= m; i ++) if(n % i == 0) {while(n % i == 0) n /= i;prime.pb(i);} if(n > 1) prime.pb(n);}LL Inclusion_exclusion(int index, LL b) {LL ret = 0, tmp, sz = prime.size();REP(i, index, sz) {tmp = b / prime[i];ret += tmp - Inclusion_exclusion(i + 1, tmp);}return ret;}int main(){#ifdef LOCAL    IN // OUT#endif    si(T);    while(T --) {    cin >> a >> b >> n;    prime.clear();    prime_init(n);    LL ans = b - a + Inclusion_exclusion(0, a - 1) - Inclusion_exclusion(0, b) + 1;    printf("Case #%d: %lld\n", ++ cas, ans);    }        return 0;}

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