<p>A <strong>sentence</strong> is a string of single-space separated words where each word consists only of lowercase letters.</p>

<p>A word is <strong>uncommon</strong> if it appears exactly once in one of the sentences, and <strong>does not appear</strong> in the other sentence.</p>

<p>Given two <strong>sentences</strong> <code>s1</code> and <code>s2</code>, return <em>a list of all the <strong>uncommon words</strong></em>. You may return the answer in <strong>any order</strong>.</p>

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

<div class="example-block">
<p><strong>Input:</strong> <span class="example-io">s1 = &quot;this apple is sweet&quot;, s2 = &quot;this apple is sour&quot;</span></p>

<p><strong>Output:</strong> <span class="example-io">[&quot;sweet&quot;,&quot;sour&quot;]</span></p>

<p><strong>Explanation:</strong></p>

<p>The word <code>&quot;sweet&quot;</code> appears only in <code>s1</code>, while the word <code>&quot;sour&quot;</code> appears only in <code>s2</code>.</p>
</div>

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

<div class="example-block">
<p><strong>Input:</strong> <span class="example-io">s1 = &quot;apple apple&quot;, s2 = &quot;banana&quot;</span></p>

<p><strong>Output:</strong> <span class="example-io">[&quot;banana&quot;]</span></p>
</div>

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

<ul>
	<li><code>1 &lt;= s1.length, s2.length &lt;= 200</code></li>
	<li><code>s1</code> and <code>s2</code> consist of lowercase English letters and spaces.</li>
	<li><code>s1</code> and <code>s2</code> do not have leading or trailing spaces.</li>
	<li>All the words in <code>s1</code> and <code>s2</code> are separated by a single space.</li>
</ul>

class Solution {
    using CntMap = unordered_map<string_view, int>;
    void find_set(CntMap& myset, const string& s){
        for(size_t i=0, j=0, N=s.size(); j<=N; ++j){
            if(j == N or s[j]==' '){
                string_view tmp(s.begin()+i, s.begin()+j);
                if(myset.count(tmp) == 0) { myset[tmp] = 1; }
                else{ ++myset[tmp];}
                i = j+1; // guaranteed: not a space
                j = i; // incremented futher
            }
        }
        // return myset;
    }
public:
    vector<string> uncommonFromSentences(const string& s1, const string& s2) {
        CntMap myset;
        find_set(myset, s1);
        find_set(myset, s2);

        // unordered_map<string_view, int> set1 = find_set(s1), set2 = find_set(s2);
        vector<string> ans;
        for(auto [sv, cnt] : myset){
            // cout << sv << ": ";
            if (cnt == 1){
                // cout << "size = " << sv.size() <<  " not found in s2..\n";
                // cout << "Put " << sv.data() << "\n";
                ans.emplace_back(sv.data(), sv.size());
            }
        }
        // cout << endl;
        // for(auto [sv, cnt] : set2){
        //     // cout << sv << " ";
        //     if(cnt == 1 and set1.count(sv) == 0){
        //         // cout << "not found in s1..\n";
        //         // cout << "Put " << sv.data() << "\n";
        //         ans.emplace_back(sv.data(), sv.size());
        //     }
        // }
        // cout << endl;
        return ans;
    }
};
8100