Problem

Given a string path, where path[i] = ’N’, ‘S’, ‘E’ or ’W’, each representing moving one unit north, south, east, or west, respectively. You start at the origin (0, 0) on a 2D plane and walk on the path specified by path.

Return True if the path crosses itself at any point, that is, if at any time you are on a location you’ve previously visited. Return False otherwise.

 

Example 1:

Input: path = “NES”

Output: false

Explanation: Notice that the path doesn’t cross any point more than once.

Example 2:

Input: path = “NESWW”

Output: true

Explanation: Notice that the path visits the origin twice.

 

Constraints:

1 <= path.length <= 10^4 path will only consist of characters in {‘N’, ‘S’, ‘E’, ‘W}

Pre analysis

Will keep map of previously visited places. and match if it occurs again