algorithms/leetcode/C#/No1487.making-file-names-unique.cs at master · ecmadao/algorithms · GitHub

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/*
 * Difficulty:
 * Medium
 *
 * Desc:
 * Given an array of strings names of size n.
 * You will create n folders in your file system such that, at the ith minute, you will create a folder with the name names[i].
 * Since two files cannot have the same name, if you enter a folder name which is previously used, the system will have a suffix addition to its name in the form of (k), where, k is the smallest positive integer such that the obtained name remains unique.
 * Return an array of strings of length n where ans[i] is the actual name the system will assign to the ith folder when you create it.
 *
 * Example 1:
 * Input: names = ["pes","fifa","gta","pes(2019)"]
 * Output: ["pes","fifa","gta","pes(2019)"]
 * Explanation:
 * Let's see how the file system creates folder names:
 * "pes" --> not assigned before, remains "pes"
 * "fifa" --> not assigned before, remains "fifa"
 * "gta" --> not assigned before, remains "gta"
 * "pes(2019)" --> not assigned before, remains "pes(2019)"
 *
 * Example 2:
 * Input: names = ["gta","gta(1)","gta","avalon"]
 * Output: ["gta","gta(1)","gta(2)","avalon"]
 * Explanation:
 * Let's see how the file system creates folder names:
 * "gta" --> not assigned before, remains "gta"
 * "gta(1)" --> not assigned before, remains "gta(1)"
 * "gta" --> the name is reserved, system adds (k), since "gta(1)" is also reserved, systems put k = 2. it becomes "gta(2)"
 * "avalon" --> not assigned before, remains "avalon"
 *
 * Example 3:
 * Input: names = ["onepiece","onepiece(1)","onepiece(2)","onepiece(3)","onepiece"]
 * Output: ["onepiece","onepiece(1)","onepiece(2)","onepiece(3)","onepiece(4)"]
 * Explanation: When the last folder is created, the smallest positive valid k is 4, and it becomes "onepiece(4)".
 *
 * Example 4:
 * Input: names = ["wano","wano","wano","wano"]
 * Output: ["wano","wano(1)","wano(2)","wano(3)"]
 * Explanation: Just increase the value of k each time you create folder "wano".
 *
 * Example 5:
 * Input: names = ["kaido","kaido(1)","kaido","kaido(1)"]
 * Output: ["kaido","kaido(1)","kaido(2)","kaido(1)(1)"]
 * Explanation: Please note that system adds the suffix (k) to current name even it contained the same suffix before.
 *
 * Constraints:
 * 1 <= names.length <= 5 * 10^4
 * 1 <= names[i].length <= 20
 * names[i] consists of lower case English letters, digits and/or round brackets.
*/

public class Solution {
    public string[] GetFolderNames(string[] names) {
        Dictionary<string, int> dict = new Dictionary<string, int>();
        string[] res = new string[names.Length];

        for (int i = 0; i < names.Length; i += 1) {
            string name = names[i];

            if (dict.ContainsKey(name)) {
                int num = dict[name];
                while (dict.ContainsKey($"{name}({dict[name]})")) dict[name] += 1;
                string newName = $"{name}({dict[name]})";
                dict[newName] = 1;
                res[i] = newName;
            } else {
                dict[name] = 1;
                res[i] = name;
            }
        }

        return res;
    }
}