522. longest special sequence II (greedy & double pointer)

522. The longest special sequence II( greedy & Double pointer )

There is a property to consider ： If the subsequence of a string is a special sequence , So the string itself is also .

The question is simplified to judge whether a string is a subsequence of other strings . Obviously greedy + Double pointer .

Time complexity ：$O(n^{2}l)$

class Solution {
    
public:
    int findLUSlength(vector<string>& a) {
    
        int n = a.size();
        int ans = -1;
        for(int k=0;k<n;k++){
    
            string s = a[k];
            int ok = 1;
            for(int i=0;i<n;i++){
    
                string t = a[i];
                if(i==k||t.size()<s.size()) continue;
            
            int pi=0,pj=0;
            int m = (int)s.size();
            int l = t.size();
            while(pi<m&&pj<l){
    
                if(s[pi]==t[pj]) pi++,pj++;
                else pj++;
            }
            if(pi==m){
    
                ok = 0;
                break;
            }
            }
            if(ok) ans=max(ans,(int)s.size());
        }
        return ans;
    }
};