Encode and Decode Strings

1package pkg5leetcode.blind75;2 3/*4 * Encode and Decode Strings | LC 2715 * APPROACH: Length-prefix encoding: len#payload for each string.6 * COMPLEXITY: Time O(total chars), Space O(total chars)7 */8import java.util.*;9 10public class blind75_LC271EncodeAndDecodeStrings {11    static String encode(List<String> strs) {12        StringBuilder sb = new StringBuilder();13        for (String s : strs) sb.append(s.length()).append('#').append(s);14        return sb.toString();15    }16 17    static List<String> decode(String s) {18        List<String> res = new ArrayList<>();19        int i = 0;20        while (i < s.length()) {21            int j = s.indexOf('#', i);22            int len = Integer.parseInt(s.substring(i, j));23            i = j + 1;24            res.add(s.substring(i, i + len));25            i += len;26        }27        return res;28    }29 30    public static void main(String[] args) {31        List<String> in = Arrays.asList("hello", "world", "leet#code");32        List<String> out = decode(encode(in));33        check(out.equals(in), "case1");34        List<String> empty = Arrays.asList("");35        check(decode(encode(empty)).equals(empty), "case2");36        System.out.println("all tests passed");37    }38 39    static void check(boolean cond, String name) {40        if (!cond) throw new AssertionError("FAILED: " + name);41        System.out.println("  PASS " + name);42    }43}