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# 題目敘述

You are given two strings word1 and word2 . Merge the strings by adding letters in alternating order, starting with word1 . If a string is longer than the other, append the additional letters onto the end of the merged string.

Return the merged string.

# Example 1

Input: word1 = “abc”, word2 = “pqr”
Output: “apbqcr”
Explanation: The merged string will be merged as so:
word1: a b c
word2: p q r
merged: a p b q c r

# Example 2

Input: word1 = “ab”, word2 = “pqrs”
Output: “apbqrs”
Explanation: Notice that as word2 is longer, “rs” is appended to the end.
word1: a b
word2: p q r s
merged: a p b q r s

# Example 3

Input: word1 = “abcd”, word2 = “pq”
Output: “apbqcd”
Explanation: Notice that as word1 is longer, “cd” is appended to the end.
word1: a b c d
word2: p q
merged: a p b q c d

# 程式碼

class Solution {
public:
    string mergeAlternately(string word1, string word2) {
       string res = "";
       int m = word1.size(), n = word2.size(); 
       int i = 0, j = 0;
       while (i < m && j < n) {
           res += word1[i];
           i++;
           res += word2[j];
           j++;
       }
       if (i != m) {
           for (; i<m; i++) res += word1[i];
       } else {
           for (; j<n; j++) res += word2[j];
       }
       return res;
    }
};
class Solution:
    def mergeAlternately(self, word1: str, word2: str) -> str:
        m, n = len(word1), len(word2)
        res = ""
        i, j = 0, 0
        while i < m and j < n:
            res += word1[i]
            i += 1
            res += word2[j]
            j += 1
        if i != m:
            while i < m:
                res += word1[i]
                i += 1
        else :
            while j < n:
                res += word2[j]
                j += 1
        return res
class Solution {
    public String mergeAlternately(String word1, String word2) {
        String res = "";
        int m = word1.length(), n = word2.length();
        int i = 0, j = 0;
        while (i < m && j < n) {
            res += word1.charAt(i);
            i++;
            res += word2.charAt(j);
            j++;
        }
        if (i != m) {
            for (; i <m; i++) res += word1.charAt(i);
        } else {
            for (; j<n; j++) res += word2.charAt(j);
        }
        return res;
    }
}