1768. 交替合并字符串

class Solution:
    def mergeAlternately(self, word1: str, word2: str) -> str:
        return ''.join(a + b for a, b in zip_longest(word1, word2, fillvalue=''))

class Solution {
    public String mergeAlternately(String word1, String word2) {
        int m = word1.length(), n = word2.length();
        StringBuilder ans = new StringBuilder();
        for (int i = 0; i < m || i < n; ++i) {
            if (i < m) {
                ans.append(word1.charAt(i));
            }
            if (i < n) {
                ans.append(word2.charAt(i));
            }
        }
        return ans.toString();
    }
}

class Solution {
public:
    string mergeAlternately(string word1, string word2) {
        int m = word1.size(), n = word2.size();
        string ans;
        for (int i = 0; i < m || i < n; ++i) {
            if (i < m) ans += word1[i];
            if (i < n) ans += word2[i];
        }
        return ans;
    }
};

func mergeAlternately(word1 string, word2 string) string {
	m, n := len(word1), len(word2)
	ans := make([]byte, 0, m+n)
	for i := 0; i < m || i < n; i++ {
		if i < m {
			ans = append(ans, word1[i])
		}
		if i < n {
			ans = append(ans, word2[i])
		}
	}
	return string(ans)
}

function mergeAlternately(word1: string, word2: string): string {
    const ans: string[] = [];
    const [m, n] = [word1.length, word2.length];
    for (let i = 0; i < m || i < n; ++i) {
        if (i < m) {
            ans.push(word1[i]);
        }
        if (i < n) {
            ans.push(word2[i]);
        }
    }
    return ans.join('');
}

impl Solution {
    pub fn merge_alternately(word1: String, word2: String) -> String {
        let s1 = word1.as_bytes();
        let s2 = word2.as_bytes();
        let n = s1.len().max(s2.len());
        let mut res = vec![];
        for i in 0..n {
            if s1.get(i).is_some() {
                res.push(s1[i]);
            }
            if s2.get(i).is_some() {
                res.push(s2[i]);
            }
        }
        String::from_utf8(res).unwrap()
    }
}

char* mergeAlternately(char* word1, char* word2) {
    int m = strlen(word1);
    int n = strlen(word2);
    char* ans = malloc(sizeof(char) * (n + m + 1));
    int i = 0;
    int j = 0;
    while (i + j != m + n) {
        if (i < m) {
            ans[i + j] = word1[i];
            i++;
        }
        if (j < n) {
            ans[i + j] = word2[j];
            j++;
        }
    }
    ans[n + m] = '\0';
    return ans;
}