stack
Easy
| Number | Note |
|---|---|
| 20. Valid Parentheses | not stack is empty, append open ones, then check closed opens whether stack is empty or pop is not correct => return false, outside, return not stack (true) |
| 225. Implement Stack using Queues | |
| 232. Implement Queue using Stacks | |
| 682. Baseball Game | |
| 844. Backspace String Compare |
Medium
Hard
| Number | Note |
|---|---|
| 32. Longest Valid Parentheses | |
| 84. Largest Rectangle in Histogram | |
| 224. Basic Calculator | |
| 895. Maximum Frequency Stack |