|412|[Fizz Buzz](https://leetcode.com/problems/fizz-buzz/)|[Solution](../../master/leetcode-algorithms/src/main/java/com/stevesun/solutions/FizzBuzz.java)| O(n)|O(1)| Easy|

|408|[Valid Word Abbreviation](https://leetcode.com/problems/valid-word-abbreviation/)|[Solution](../../master/leetcode-algorithms/src/main/java/com/stevesun/solutions/ValidWordAbbreviation.java)| O(n)|O(1)| Easy|

|404|[Sum of Left Leaves](https://leetcode.com/problems/sum-of-left-leaves/)|[Solution](../../master/leetcode-algorithms/src/main/java/com/stevesun/solutions/SumofLeftLeaves.java)| O(n)|O(h)| Easy|

|401|[Binary Watch](https://leetcode.com/problems/binary-watch/)|[Solution](../../master/leetcode-algorithms/src/main/java/com/stevesun/solutions/BinaryWatch.java)| O(1)|O(1)| Easy|

|398|[Random Pick Index](https://leetcode.com/problems/random-pick-index/)|[Solution](../../master/leetcode-algorithms/src/main/java/com/stevesun/solutions/RandomPickIndex.java) | | | Medium| Reservoir Sampling

|397|[Integer Replacement](https://leetcode.com/problems/integer-replacement/)|[Solution](../../master/leetcode-algorithms/src/main/java/com/stevesun/solutions/IntegerReplacement.java)| ? | ? | Easy| BFS

|396|[Rotate Function](https://leetcode.com/problems/rotate-function/)|[Solution](../../master/leetcode-algorithms/src/main/java/com/stevesun/solutions/RotateFunction.java)| O(n^2) could be optimized to O(n)| O(1)| Easy|

packagecom.stevesun;

importjava.util.ArrayList;

importjava.util.List;

publicclassBinaryWatch {

publicList<String>readBinaryWatch(intnum) {

List<String>times =newArrayList<>();

for (inth =0;h <12;h++) {

for (intm =0;m <60;m++) {

if (Integer.bitCount(h*60 +m) ==num)times.add(String.format("%d:%02d",h,m));//%02 means to pad this two-digit decimal number on the left with zeroes

}

}

returntimes;

}

}