problems/strings.js

A set of problems that can be encountered in interviews.

/**
 * Can you check to see if a string contains only unique characters.  No
 * other datastructures than arrays can be used.
 *
 * @param  {String} str
 * @return {Boolean}
 */
function isUnique(str) {
    var contains = [];
    for (var i = 0; i < str.length; i++) {
        var code = str.charCodeAt(i);
        if (contains[code]) {
            return false;
        }
        contains[code] = true;
    }
    return true;
}

/**
 * Remove any non unique characters.
 *
 * Same as algorithm isUnique except for we remove those strs.
 * @param  {String} str
 * @return {String}
 */
 function removeNonUnique(str) {
    var contains = [];
    var newStr = [];

    for (var i = 0; i < str.length; i++) {
        var code = str.charCodeAt(i);
        if (!contains[code]) {
            newStr.push(str.charAt(i));
        }
        contains[code] = true;
    }
    return newStr.join('');
 }