LeetCode 650 2 Keys Keyboard

题目：

Initially on a notepad only one character 'A' is present. You can perform two operations on this notepad for each step:

1. Copy All: You can copy all the characters present on the notepad (partial copy is not allowed).
2. Paste: You can paste the characters which are copied last time.

Given a number n. You have to get exactly n 'A' on the notepad by performing the minimum number of steps permitted. Output the minimum number of steps to get n 'A'.

Example 1:

Input: 3Output: 3Explanation:Intitally, we have one character 'A'.In step 1, we use Copy All operation.In step 2, we use Paste operation to get 'AA'.In step 3, we use Paste operation to get 'AAA'.

Note:

1. The n will be in the range [1, 1000].

题意：

初始字符串为“A”，只有两种操作允许：

1. Copy All：把当前所有的字符复制
2. Paste：把最后一次复制的字符串粘贴

问最少经过多少步可以把初始字符串变成给定 n 个’A'的字符串。

n的范围是 [1, 1000]

可以当作模拟来做，对于每次都有两种情况，复制和粘贴，分别进行模拟。

尝试过dp，没改出来，，差点火候，还是要练习啊

代码如下：

class Solution {public:    int ans = 999999999;void dfs(int now, int copy, int step, int n) {    if (now == n) {    ans = min(ans, step);    }    else if (now > n) return;    if (copy != 0)dfs(now + copy, copy, step + 1, n);    if (now != copy)dfs(now, now, step + 1, n);        }    int minSteps(int n) {dfs(1, 0, 0, n);return ans;    }};