Codeforces 597A Divisibility 【数学计数】

A. Divisibility

time limit per test

1 second

memory limit per test

256 megabytes

input

standard input

output

standard output

Find the number of k-divisible numbers on the segment [a, b]. In other words you need to find the number of such integer values x thata ≤ x ≤ b and x is divisible by k.

Input

The only line contains three space-separated integers k, a and b (1 ≤ k ≤ 1018; - 1018 ≤ a ≤ b ≤ 1018).

Output

Print the required number.

Sample test(s)

input

1 1 10

output

10

input

2 -4 4

output

5

题意：给定区间[x, y]，问你区间里面能够被k整除的数有多少个。

思路：把端点全转化为正整数来算就好了。要不会WA到死。。。

AC代码：

#include <cstdio>#include <cstring>#include <cmath>#include <cstdlib>#include <algorithm>#include <queue>#include <stack>#include <map>#include <vector>#define INF 0x3f3f3f3f#define eps 1e-8#define MAXN (100000+10)#define MAXM (50000000)#define Ri(a) scanf("%d", &a)#define Rl(a) scanf("%lld", &a)#define Rf(a) scanf("%lf", &a)#define Rs(a) scanf("%s", a)#define Pi(a) printf("%d\n", (a))#define Pf(a) printf("%lf\n", (a))#define Pl(a) printf("%lld\n", (a))#define Ps(a) printf("%s\n", (a))#define W(a) while(a--)#define CLR(a, b) memset(a, (b), sizeof(a))#define MOD 1000000007#define LL long long#define lson o<<1, l, mid#define rson o<<1|1, mid+1, r#define ll o<<1#define rr o<<1|1using namespace std;int main(){    LL k, a, b;    Rl(k); Rl(a); Rl(b);    LL ans;    if(a <= 0 && b <= 0)    {        swap(a, b);        a = -a; b = -b;    }    if(a <= 0 && b >= 0)    {        a = -a;        ans = 1 + b / k + a / k;    }    else        ans = b / k - (a-1) / k;    Pl(ans);    return 0;}