最长公共字串

    var longestCommonPrefix = function (strs) {
        if (strs.length == 0) return '';
        let ans = strs[0];
        for (let i = 1; i < strs.length; i++) {
            let j = 0;
            for (; j < ans.length && j < strs[i].length; j++) {
                if (ans[j] != strs[i][j])
                    break;
            }
            ans = ans.substr(0, j);
            if (ans === "")
                return ans;
        }
        return ans;
    };
     console.log(longestCommonPrefix(["dog","racecar","car"]));

    var longestCommonPrefixs = function (str) {
        if (!str.length) return '';
        let res = str[0];
        for (ch of str) {
            for (let i = 0; i < res.length; i++) {
                if (ch[i] !== res[i]) {
                    res = res.slice(0, i);
                    break;
                }
            }
        }
        return res;
    };
    console.log(longestCommonPrefixs(["flowers", "flow", "flight"]));