Sync LeetCode submission Runtime - 0 ms (100.00%), Memory - 10 MB (20.35%)

Author: koralkulacoglu

LeetCode/0401-binary-watch/README.md

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+<p>A binary watch has 4 LEDs on the top to represent the hours (0-11), and 6 LEDs on the bottom to represent&nbsp;the minutes (0-59). Each LED represents a zero or one, with the least significant bit on the right.</p>
+
+<ul>
+	<li>For example, the below binary watch reads <code>&quot;4:51&quot;</code>.</li>
+</ul>
+
+<p><img alt="" src="https://assets.leetcode.com/uploads/2021/04/08/binarywatch.jpg" style="width: 500px; height: 500px;" /></p>
+
+<p>Given an integer <code>turnedOn</code> which represents the number of LEDs that are currently on (ignoring the PM), return <em>all possible times the watch could represent</em>. You may return the answer in <strong>any order</strong>.</p>
+
+<p>The hour must not contain a leading zero.</p>
+
+<ul>
+	<li>For example, <code>&quot;01:00&quot;</code> is not valid. It should be <code>&quot;1:00&quot;</code>.</li>
+</ul>
+
+<p>The minute must&nbsp;consist of two digits and may contain a leading zero.</p>
+
+<ul>
+	<li>For example, <code>&quot;10:2&quot;</code> is not valid. It should be <code>&quot;10:02&quot;</code>.</li>
+</ul>
+
+<p>&nbsp;</p>
+<p><strong class="example">Example 1:</strong></p>
+<pre><strong>Input:</strong> turnedOn = 1
+<strong>Output:</strong> ["0:01","0:02","0:04","0:08","0:16","0:32","1:00","2:00","4:00","8:00"]
+</pre><p><strong class="example">Example 2:</strong></p>
+<pre><strong>Input:</strong> turnedOn = 9
+<strong>Output:</strong> []
+</pre>
+<p>&nbsp;</p>
+<p><strong>Constraints:</strong></p>
+
+<ul>
+	<li><code>0 &lt;= turnedOn &lt;= 10</code></li>
+</ul>

LeetCode/0401-binary-watch/solution.cpp

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+class Solution {
+    void getTime(int binary, vector<string>& res) {
+        int hour = (binary & 0b1111000000) >> 6;
+        int minute = binary & 0b111111;
+        if (hour > 11 || minute > 59) return;
+        string time = to_string(hour) + (minute < 10 ? ":0" : ":") + to_string(minute);
+        res.push_back(time);
+    }
+
+public:
+    vector<string> readBinaryWatch(int turnedOn) {
+        vector<string> res;
+        for (int i=0; i<1024; i++) {
+            if (__builtin_popcount(i) == turnedOn) getTime(i, res);
+        }
+        return res;
+    }
+};