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;
}