PROBLEM DESCRIPTION
You are given a string s and an array of strings words.
You should add a closed pair of bold tag <b> and </b> to wrap the substrings in s that exist in words.
- If two such substrings overlap, you should wrap them together with only one pair of closed bold-tag.
- If two substrings wrapped by bold tags are consecutive, you should combine them.
Return s after adding the bold tags.
SOLUTION
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class Solution {
public String addBoldTag(String s, String[] words) {
// Create a boolean array 'bold' to mark which characters in 's' should be bolded.
boolean[] bold = new boolean[s.length()];
// Iterate through the array of words to find and mark their occurrences in 's'.
for (int i = 0; i < words.length; i++) {
String word = words[i];
// Find the first occurrence of 'word' in 's'.
int idx = s.indexOf(word);
// mark all positions corresponding to the current word in string s as bold
while (idx != -1) {
for (int j = idx; j <= idx + word.length() - 1; j++) {
bold[j] = true;
}
// Find the next occurrence of 'word' in 's'.
idx = s.indexOf(word, idx + 1);
}
}
String openTag = "<b>";
String closeTag = "</b>";
// answer string
StringBuffer sb = new StringBuffer();
// go through each position to check if it should be bold
for (int i = 0; i < bold.length; i++) {
if (bold[i] == true) {
// If the current character should be bolded and it's the start of a new bolded sequence.
if (i == 0 || bold[i - 1] == false) {
sb.append(openTag);
}
}
// Append the current character to the result.
sb.append(s.charAt(i));
if (bold[i] == true) {
// If the current character should be bolded and it's the end of a bolded sequence.
if (i == bold.length - 1 || bold[i + 1] == false) {
sb.append(closeTag);
}
}
}
return sb.toString();
}
}