String Compression

1package pkg5leetcode.official75;2 3/*4 * String Compression | LC 4435 * APPROACH: In-place write char then count digits.6 * COMPLEXITY: Time O(n), Space O(1)7 */8public class official75_LC443StringCompression {9    static int compress(char[] chars) {10        int write = 0, read = 0;11        while (read < chars.length) {12            char c = chars[read];13            int count = 0;14            while (read < chars.length && chars[read] == c) { read++; count++; }15            chars[write++] = c;16            if (count > 1) {17                for (char d : String.valueOf(count).toCharArray()) chars[write++] = d;18            }19        }20        return write;21    }22 23    public static void main(String[] args) {24        char[] a = {'a','a','b','b','c','c','c'};25        check(compress(a) == 6 && a[0]=='a' && a[1]=='2' && a[2]=='b', "case1");26        char[] b = {'a'};27        check(compress(b) == 1 && b[0]=='a', "case2");28        System.out.println("all tests passed");29    }30 31    static void check(boolean cond, String name) {32        if (!cond) throw new AssertionError("FAILED: " + name);33        System.out.println("  PASS " + name);34    }35}