求一个区间有多少个数能整除k

Time Limit:1000MS Memory Limit:262144KB 64bit IO Format:%I64d & %I64u
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Status

Practice

CodeForces 597A
Description
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 that a ≤ 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 Input
Input
1 1 10
Output
10
Input
2 -4 4
Output

5

#include  
int main()  
{  
    long long k,a,b;  
    while(scanf("%lld%lld%lld",&k,&a,&b)!=EOF)  
    {  
        long long s=0;  
        if(b<0)  
        {  
            a=-a;b=-b;  
            long long t=a;  
            a=b;  
            b=t;  
        }  
        s=b/k-a/k;  
        if(a%k==0||a<=0)  //如果a能整除k，或这个区间包括0 
           s++;  
        printf("%lld\n",s);  
    }
    return 0;  
}