LeetCode之Letter Tile Possibilities（Kotlin）

问题：

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方法：
深度优先遍历加染色提高遍历效率。

package com.eric.leetcode

class LetterTilePossibilities {
    fun numTilePossibilities(tiles: String): Int {
        val visit = BooleanArray(tiles.length) {false}
        val result = mutableSetOf()
        dfs(visit, tiles, "", result)
        return result.size - 1
    }

    private fun dfs(visit: BooleanArray, tiles: String, series: String, result: MutableSet) {
        for (index in visit.indices) {
            if (visit[index]) {
                continue
            }
            visit[index] = true
            dfs(visit, tiles, series + tiles[index], result)
            visit[index] = false
        }
        result.add(series)
    }
}

fun main() {
    val letterTilePossibilities = LetterTilePossibilities()
    print(letterTilePossibilities.numTilePossibilities("VV"))
}

有问题随时沟通

具体代码实现可以参考Github