CodeForces-916A-jamie and Alarm Snooze(笨比题目)

链接:

https://vjudge.net/problem/CodeForces-916A

题意:

Jamie loves sleeping. One day, he decides that he needs to wake up at exactly hh: mm. However, he hates waking up, so he wants to make waking up less painful by setting the alarm at a lucky time. He will then press the snooze button every x minutes until hh: mm is reached, and only then he will wake up. He wants to know what is the smallest number of times he needs to press the snooze button.

A time is considered lucky if it contains a digit '7'. For example, 13: 07 and 17: 27 are lucky, while 00: 48 and 21: 34 are not lucky.

Note that it is not necessary that the time set for the alarm and the wake-up time are on the same day. It is guaranteed that there is a lucky time Jamie can set so that he can wake at hh: mm.

Formally, find the smallest possible non-negative integer y such that the time representation of the time x·y minutes before hh: mm contains the digit '7'.

Jamie uses 24-hours clock, so after 23: 59 comes 00: 00.

思路:

开始以为按几下可以变到7...没想到是往前,还只能往前.

代码:

#include <bits/stdc++.h>
using namespace std;

bool Solve(int h, int m)
{
    while (h)
    {
        if (h%10 == 7)
            return true;
        h /= 10;
    }
    while (m)
    {
        if (m%10 == 7)
            return true;
        m /= 10;
    }
    return false;
}

int main()
{
    int x, h, m, h1, m1;
    cin >> x >> h >> m;
    h1 = h, m1 = m;
    int cnt = 0, cnt1 = 0;
    while (!Solve(h1, m1))
    {
        m1 -= x;
        if (m1 < 0)
            h1--, m1 = 60+m1;
        if (h1 < 0)
            h1 = 24+h1;
        cnt1++;
    }
    cout << cnt1 << endl;

    return 0;
}