1496. Path Crossing

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}

思路：

题目意思是给出一个字符串，每一位代表可以往一个方向走一步，让判断所走的路线是否会交叉，很简单的实现题，遍历字符串，直用一个map记录所走过的坐标就可以。

golang:

func isPathCrossing(path string) bool {
    if len(path) == 0 {
        return true
    }

    var point = [2]int{0, 0}
    var dict = map[[2]int]bool {
        point: true,
    }
    for _, p := range path {
        if p == 'N' {
            point[0]++
        } else if p == 'S' {
            point[0]--
        } else if p == 'E' {
            point[1]++
        } else if p == 'W' {
            point[1]--
        }
        if _, ok := dict[point]; ok {
            return true
        }
        dict[point] = true
    }
    
    return false
}