Explanation: We only have to add one minute to current, so the minimum number of operations needed is 1.

Constraints

current and correct are in the format "HH:MM"
current <= correct

Solution

Method 1 – Greedy (Largest Step First)

Intuition

Convert both times to minutes, then use the largest possible step (60, 15, 5, 1) at each stage to minimize the number of operations.

Approach

Parse both times to minutes.
Compute the difference.
For each step in [60, 15, 5, 1], use as many as possible, subtract, and count.
Return the total count.

Code

[{"language":"C++","code":"#include <string>\nusing namespace std;\nclass Solution {\npublic:\n    int convertTime(string current, string correct) {\n        int c = stoi(current.substr(0,2)) * 60 + stoi(current.substr(3,2));\n        int t = stoi(correct.substr(0,2)) * 60 + stoi(correct.substr(3,2));\n        int diff = t - c, ans = 0;\n        for (int step : {60, 15, 5, 1}) {\n            ans += diff / step;\n            diff %= step;\n        }\n        return ans;\n    }\n};","lang":"cpp","html":"<pre class=\"shiki shiki-themes github-light github-dark\" style=\"background-color:#fff;--shiki-dark-bg:#24292e;color:#24292e;--shiki-dark:#e1e4e8\" tabindex=\"0\"><code><span class=\"line\"><span style=\"color:#D73A49;--shiki-dark:#F97583\">#include</span><span style=\"color:#032F62;--shiki-dark:#9ECBFF\"> &#x3C;string></span></span>\n<span class=\"line\"><span style=\"color:#D73A49;--shiki-dark:#F97583\">

Related Tags