Colidity--CountDiv

很巧妙的思路：先计算A之前的被K除的最大数，然后计算B-A之间能填充多少个K

// you can use includes, for example:
// #include <algorithm>

// you can write to stdout for debugging purposes, e.g.
// cout << "this is a debug message" << endl;

int solution(int A, int B, int K) {
    // write your code in C++11
    if(A % K ==0)
    {
        return (B-A)/K+1;//加上A
    }
    else
    {
        return (B-(A-A%K))/K;
    }
}