feat(src): add 401-readBinaryWatch

Author: kwu130

src/401-readBinaryWatch.cpp

@@ -0,0 +1,39 @@
+//
+// Created by 1412 on 2026/4/11.
+//
+
+#include <bits/stdc++.h>
+#include "common.h"
+
+using namespace std;
+
+class Solution {
+public:
+    vector<string> readBinaryWatch(int turnedOn) {
+        vector<string> res;
+        for (int h = 0; h < 12; h++) {
+            for (int m = 0; m < 60; m++) {
+                if (__builtin_popcount(h) + __builtin_popcount(m) == turnedOn) {
+                    res.push_back(to_string(h) + ":" + (m < 10 ? "0" : "") + to_string(m));
+                }
+            }
+        }
+        return res;
+    }
+};
+
+void test() {
+    Solution s;
+    vector<string> expected = {"0:01", "0:02", "0:04", "0:08", "0:16", "0:32", "1:00", "2:00", "4:00", "8:00"};
+    vector<string> res = s.readBinaryWatch(1);
+    assert(compareHelper::equalIgnoreOrder(res, expected));
+
+    expected = {};
+    res = s.readBinaryWatch(9);
+    assert(compareHelper::equalIgnoreOrder(res, expected));
+}
+
+int main() {
+    test();
+    return 0;
+}