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 <= 104path[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)
}