389_FindtheDifference - a920604a/leetcode GitHub Wiki

---

title: 389. Find the Difference

tags:
- Bit Manipulation categories: leetcode comments: false

problem

給定兩字串，字串t比字串s多出一個字元，將他找出來

solution

• 逐一字串 t 拜訪，拜訪到的字元將轉其對應ASCII 取值，並累加
• 逐一字串 s 拜訪，拜訪到的字元將轉其對應ASCII 取值，並相減

class Solution {
public:
    char findTheDifference(string s, string t) {
        int ret = 0;
        for(char c:t) ret +=c; // auto cast
        for(char c:s) ret -=c; 
        return (char)ret;
    }
};

• 遍歷字串s,t，對所有字元做xor

class Solution {
public:
    char findTheDifference(string s, string t) {
        char ret =0;
        for(char c:t) ret ^=c;
        for(char c:s) ret ^=c; 
        return ret;
        
    }
};

analysis

• time complexity O(n)
• space complexity O(1)