codeforces 569A Music

题目连接

歌曲下载速度ds = （q-1)/q

歌曲播放速度ps = 1

则当前已下载好s秒的情况下，歌曲播放进度追上下载进度是歌曲播放到的位置pp = s / (ps - ds) = s * (1 - (q-1)/q) = s*q;

code:

#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;

int main()
{
    int T,startPlayTime,q;
    int downSpeed;
    int playSpeed = 1;
    int dx;
    while(cin >> T >> startPlayTime >> q){
        int cnt = 0;
        dx = startPlayTime ;
        while(dx < T){
            dx = dx * q;
            cnt ++;
        }
        cout << cnt << endl;
    }
        return 0;
}