LeetCode in Kotlin

1496. Path Crossing

Easy

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 have 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 <= 104
• path[i] is either 'N', 'S', 'E', or 'W'.

Solution

class Solution {
    fun isPathCrossing(path: String): Boolean {
        val visited = ArrayDeque<Coord>()
        visited.add(Coord(0, 0))
        for (c in path.toCharArray()) {
            val last = visited.last()
            if (c == 'N') {
                val nextStep = Coord(last.x, last.y + 1)
                if (visited.contains(nextStep)) {
                    return true
                }
                visited.add(nextStep)
            } else if (c == 'S') {
                val nextStep = Coord(last.x, last.y - 1)
                if (visited.contains(nextStep)) {
                    return true
                }
                visited.add(nextStep)
            } else if (c == 'E') {
                val nextStep = Coord(last.x - 1, last.y)
                if (visited.contains(nextStep)) {
                    return true
                }
                visited.add(nextStep)
            } else if (c == 'W') {
                val nextStep = Coord(last.x + 1, last.y)
                if (visited.contains(nextStep)) {
                    return true
                }
                visited.add(nextStep)
            }
        }
        return false
    }

    internal data class Coord(var x: Int, var y: Int)
}

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