- weird sorting
- take an array and sort it by alpha code
- take a square matrix and sort it in diagonal order
- query hash
- take an array of pairs and an array of commands then perform the commands on each pair when the command matches some condition of the pair
- measure the perimeter of the island
- take a matrix of land cells and return the number of edges
- escape the maze
- take a matrix of maze cells and return the directions out of the maze
- do something every nth time on a very long array (10^20)
- gradually speed up by skipping more
- implement time in words 1:30 == "half past one"
- implement chmod recursive on a list of files
- take a stream of file permission change events from audit log and report the occurance of each type of change in percent total and percent recent