1736, Merge string aternatively(Leetcode).cpp

class Solution {
public:
    string mergeAlternately(string word1, string word2) {
        int n=word1.size(), m=word2.size();
        string res="";
        int i=0, j=0;
        while(i<n && j<m){
            res+=word1[i++];
            res+=word2[j++]; 
        }
        while(i<n){
            res+=word1[i++];
        }
        while(j<m){
            res+=word2[j++];
        }

        return res;
    }
};