1768. Merge Strings Alternately

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
 

Constraints:

1 <= word1.length, word2.length <= 100
word1 and word2 consist of lowercase English letters.

这题相对而言还是比较简单的，交叉放字符即可。当一个字符放完之后，把另一个字符所有的字符放入即可。

class MergeStringsAlternately : public Solution {
public:
    void Exec() {
        
    }
    string mergeAlternately(string word1, string word2) {
        string res;
        int i1 = 0, i2 = 0, size = std::max(word1.size(), word2.size());
        for (int i = 0; i < size; i++) {
            if (i1 < word1.size())
                res.push_back(word1[i1++]);
            else {
                if (i2 < word2.size()) {
                    res += word2.substr(i2, word2.size() - 1 - i2 + 1);
                    break;
                }
            }
            if (i2 < word2.size())
                res.push_back(word2[i2++]);
            else {
                if (i1 < word1.size()) {
                    res += word1.substr(i1, word1.size() - 1 - i1 + 1);
                    break;
                }
            }
        }
        return res;
    }
};