<p>Given a string <code>s</code> and a dictionary of strings <code>wordDict</code>, add spaces in <code>s</code> to construct a sentence where each word is a valid dictionary word. Return all such possible sentences in <strong>any order</strong>.</p>

<p><strong>Note</strong> that the same word in the dictionary may be reused multiple times in the segmentation.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> s = &quot;catsanddog&quot;, wordDict = [&quot;cat&quot;,&quot;cats&quot;,&quot;and&quot;,&quot;sand&quot;,&quot;dog&quot;]
<strong>Output:</strong> [&quot;cats and dog&quot;,&quot;cat sand dog&quot;]
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> s = &quot;pineapplepenapple&quot;, wordDict = [&quot;apple&quot;,&quot;pen&quot;,&quot;applepen&quot;,&quot;pine&quot;,&quot;pineapple&quot;]
<strong>Output:</strong> [&quot;pine apple pen apple&quot;,&quot;pineapple pen apple&quot;,&quot;pine applepen apple&quot;]
<strong>Explanation:</strong> Note that you are allowed to reuse a dictionary word.
</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> s = &quot;catsandog&quot;, wordDict = [&quot;cats&quot;,&quot;dog&quot;,&quot;sand&quot;,&quot;and&quot;,&quot;cat&quot;]
<strong>Output:</strong> []
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= s.length &lt;= 20</code></li>
	<li><code>1 &lt;= wordDict.length &lt;= 1000</code></li>
	<li><code>1 &lt;= wordDict[i].length &lt;= 10</code></li>
	<li><code>s</code> and <code>wordDict[i]</code> consist of only lowercase English letters.</li>
	<li>All the strings of <code>wordDict</code> are <strong>unique</strong>.</li>
	<li>Input is generated in a way that the length of the answer doesn&#39;t exceed&nbsp;10<sup>5</sup>.</li>
</ul>

class Solution {
public:
    struct QueueItem {
        int head;
        std::string string;
    };

    void wordBreakRec(
        std::string_view s,
        const std::vector<std::string>& word_dict,
        std::string cur,
        std::vector<std::string>& result
    ) {
        if(s == "") {
            result.push_back(cur);
            return;
        }

        auto range_begin = word_dict.begin();
        auto range_end = word_dict.end();

        int char_index = 0;
        while(char_index < static_cast<int>(s.size())) {
            auto lower_bound = std::lower_bound(
                range_begin,
                range_end,
                s[char_index],
                [char_index](const std::string& a, char b) {
                    return a[char_index] < b;
                }
            );

            auto upper_bound = std::upper_bound(
                range_begin,
                range_end,
                s[char_index],
                [char_index](char b, const std::string& a) {
                    return b < a[char_index];
                }
            );

            if(lower_bound == upper_bound) {
                return;
            }

            if(char_index + 1 == lower_bound->size()) {
                std::string rec_str = cur.empty()
                    ? *lower_bound
                    : cur + " " + *lower_bound;

                wordBreakRec(s.substr(lower_bound->size()), word_dict, rec_str, result);
                lower_bound++;

                if(lower_bound == upper_bound) {
                   return;
                }
            }

            range_begin = lower_bound;
            range_end = upper_bound;
            char_index++;
        }
    }

    vector<string> wordBreak(string s, vector<string>& wordDict) {
        std::sort(wordDict.begin(), wordDict.end());
        std::vector<std::string> result;
        wordBreakRec(s, wordDict, "", result);
        return result;
    }
};
9000