Time Limit: Java: 2000 ms / Others: 2000 ms
Memory Limit: Java: 65536 KB / Others: 65536 KB
What's the maximum number of regions definable by N zig-zag lines, each of
which consists of two parallel infinite half-lines joined by a straight line
Here is an example of 2 zig-zag lines yield 12 regions at the most.