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36 lines
874 B
36 lines
874 B
/**
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* File: climbing_stairs_dfs_mem.kt
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* Created Time: 2024-01-25
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* Author: curtishd (1023632660@qq.com)
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*/
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package chapter_dynamic_programming
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/* 记忆化搜索 */
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fun dfs(i: Int, mem: IntArray): Int {
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// 已知 dp[1] 和 dp[2] ，返回之
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if (i == 1 || i == 2) return i
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// 若存在记录 dp[i] ，则直接返回之
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if (mem[i] != -1) return mem[i]
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// dp[i] = dp[i-1] + dp[i-2]
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val count = dfs(i - 1, mem) + dfs(i - 2, mem)
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// 记录 dp[i]
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mem[i] = count
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return count
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}
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/* 爬楼梯：记忆化搜索 */
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fun climbingStairsDFSMem(n: Int): Int {
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// mem[i] 记录爬到第 i 阶的方案总数，-1 代表无记录
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val mem = IntArray(n + 1)
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mem.fill(-1)
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return dfs(n, mem)
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}
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/* Driver Code */
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fun main() {
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val n = 9
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val res = climbingStairsDFSMem(n)
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println("爬 $n 阶楼梯共有 $res 种方案")
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} |