RemoveComments.java

package LeetCodeJava.String;

import java.util.ArrayList;
import java.util.List;

// https://leetcode.com/problems/remove-comments/description/
// https://leetcode.ca/all/722.html
public class RemoveComments {

    // V0
    // TODO : implement
//    public List<String> removeComments(String[] source) {
//
//    }

    // V1
    // IDEA : PARSING
    // https://leetcode.com/problems/remove-comments/editorial/
    public List<String> removeComments_1(String[] source) {
        boolean inBlock = false;
        StringBuilder newline = new StringBuilder();
        List<String> ans = new ArrayList();
        for (String line: source) {
            int i = 0;
            char[] chars = line.toCharArray();
            if (!inBlock) {
                newline = new StringBuilder();
            }
            while (i < line.length()) {
                if (!inBlock && i+1 < line.length() && chars[i] == '/' && chars[i+1] == '*') {
                    inBlock = true;
                    i++;
                } else if (inBlock && i+1 < line.length() && chars[i] == '*' && chars[i+1] == '/') {
                    inBlock = false;
                    i++;
                } else if (!inBlock && i+1 < line.length() && chars[i] == '/' && chars[i+1] == '/') {
                    break;
                } else if (!inBlock) {
                    newline.append(chars[i]);
                }
                i++;
            }
            if (!inBlock && newline.length() > 0) {
                ans.add(new String(newline));
            }
        }
        return ans;
    }


    // V2
    // https://leetcode.ca/2017-11-21-722-Remove-Comments/
    public List<String> removeComments_2(String[] source) {
        List<String> ans = new ArrayList<>();
        StringBuilder sb = new StringBuilder();
        boolean blockComment = false;
        for (String s : source) {
            int m = s.length();
            for (int i = 0; i < m; ++i) {
                if (blockComment) {
                    if (i + 1 < m && s.charAt(i) == '*' && s.charAt(i + 1) == '/') {
                        blockComment = false;
                        ++i;
                    }
                } else {
                    if (i + 1 < m && s.charAt(i) == '/' && s.charAt(i + 1) == '*') {
                        blockComment = true;
                        ++i;
                    } else if (i + 1 < m && s.charAt(i) == '/' && s.charAt(i + 1) == '/') {
                        break;
                    } else {
                        sb.append(s.charAt(i));
                    }
                }
            }
            if (!blockComment && sb.length() > 0) {
                ans.add(sb.toString());
                sb.setLength(0);
            }
        }
        return ans;
    }

}