1047. Remove All Adjacent Duplicates In String

Easy

You are given a string s consisting of lowercase English letters. A duplicate removal consists of choosing two adjacent and equal letters and removing them.

We repeatedly make duplicate removals on s until we no longer can.

Return the final string after all such duplicate removals have been made. It can be proven that the answer is unique.

Example 1:

Input: s = "abbaca"
Output:
 "ca"
Explanation:
 
For example, in "abbaca" we could remove "bb" since the letters are adjacent and equal, and this is the only possible move.  The result of this move is that the string is "aaca", of which only "aa" is possible, so the final string is "ca".

Example 2:

Input: s = "azxxzy"
Output:
 "ay"

Constraints:

• 1 <= s.length <= 105

• s consists of lowercase English letters.

解題

這題使用到stack來做，如果stack尾巴的值和要放進去的值相同，就把這兩個值都移除。下面是我的方法

func removeDuplicates(s string) string {
    if len(s)<=1 { return s }
    
    ans := s[:1]
    
    for i:=1; i<len(s); i++ {
        if len(ans)==0 || string(s[i])!= ans[len(ans)-1] {
            ans += string(s[i])
        } else {
            ans = ans[:len(ans)-1]
        }
    }
    
    return ans
}

雖然邏輯差不多，但是用[]byte會更快且省空間：

func removeDuplicates(s string) string {
    if len(s)<=1 { return s }
    
    ans := make([]byte, 0)
    ans = append(ans, s[0])
    
    for i:=1; i<len(s); i++ {
        if len(ans)==0 || s[i]!= ans[len(ans)-1] {
            ans = append(ans, s[i])
        } else {
            ans = ans[:len(ans)-1]
        }
    }
    
    return string(ans)
}