hdu 4614（数学 + 乱搞）

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cstdlib>
#include <cmath>

using namespace std;

typedef long long LL;

LL calc(int n, int a, int b) {
	LL ans = 0;
	int d = 0;
	int ta = a, tb = b;
	int p = 0;

	while (p < n) {
		if (tb < ta) {
			ans += (LL)d * (min(tb, n) - p);
			p = tb;
			d = labs((p % a) - (p % b));
			tb += b;	
		}
		else {
			ans += (LL)d * (min(ta, n) - p);
			p = ta;
			d = labs((p % a) - (p % b));
			ta += a;		
		}	
	}

	return ans;
}

LL gcd(LL a, LL b) {
	return b == 0 ? a : gcd(b, a % b);
}

LL lcm(LL a, LL b) {
	return a / gcd(a, b) * b;
}

int main() {
	int test, n, a, b;
	LL r;

	scanf("%d", &test);
	while (test--) {
		scanf("%d%d%d", &n, &a, &b);
		if (a == b) {
			puts("0");
			continue;
		}
		r = lcm(a, b);
		LL tmp = calc(r, a, b);
		LL res = n / r * tmp + calc(n % r, a, b);
		printf("%I64d\n", res);
	}
	return 0;
}