My solved challenges and hacks (with Go, Python and Java)
-Data structures (maps, container/ list, heap, tries, graphs, tree, sorting, priority queues, binary search)
-Generate Go code with encoding/gob
-Open, Create files with package "os"
-Read input and write output with package "bufio"
-Read/write png,jpg images "io"
-Regular expressions and string manipulation "strings" "strconv"
-Big integers "math/big"
-Goroutines, channels and concurrency