hello-algo/codes/javascript/chapter_dynamic_programming/climbing_stairs_dfs_mem.js

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/**
* File: climbing_stairs_dfs_mem.js
* Created Time: 2023-07-26
* Author: yuan0221 (yl1452491917@gmail.com)
*/
/* 记忆化搜索 */
function dfs(i, mem) {
// 已知 dp[1] 和 dp[2] ,返回之
if (i == 1 || i == 2) return i;
// 若存在记录 dp[i] ,则直接返回之
if (mem[i] != -1) return mem[i];
// dp[i] = dp[i-1] + dp[i-2]
const count = dfs(i - 1, mem) + dfs(i - 2, mem);
// 记录 dp[i]
mem[i] = count;
return count;
}
/* 爬楼梯:记忆化搜索 */
function climbingStairsDFSMem(n) {
// mem[i] 记录爬到第 i 阶的方案总数,-1 代表无记录
const mem = new Array(n + 1).fill(-1);
return dfs(n, mem);
}
/* Driver Code */
const n = 9;
const res = climbingStairsDFSMem(n);
console.log(`${n} 阶楼梯共有 ${res} 种方案`);