General Bug Summary

• char doesn't have empty one, which means there is no expression like:

char c = '';

• Binary Search question: definitely make sure the return value is the index or the value on the position. *[Binary Search] should assign mid idx to left, right, rather than assign left or right idx to mid;

// Right way:
if (array[mid] < target) {
    left = mid;
} else {
    right = mid;
}

// Wrong way:
if (array[mid] < target) {
    mid = left;
} else {
    mid = right;
}

• When you want to get average. Please don't forget to change int to double first. Otherwise, you may lose the precision. (346. Moving Average from Data Stream https://leetcode.com/problems/moving-average-from-data-stream/description/)

• For some stack question, you may need to check peek() to see if you will push element to stack or not. Do not forget stack or queue empty time

Need to research

• LinkedList, ArrayDeque; Queue, Deque difference
• https://leetcode.com/problems/sliding-window-median/solution/