You are given an array of strings arr. A string s is formed by the concatenation of a subsequence of arr that has unique characters.
Return the maximum possible length of s.
A subsequence is an array that can be derived from another array by deleting some or no elements without changing the order of the remaining elements.
Example 1:
Input: arr = ["un","iq","ue"]
Output: 4
Explanation: All the valid concatenations are:
- ""
- "un"
- "iq"
- "ue"
- "uniq" ("un" + "iq")
- "ique" ("iq" + "ue")
Maximum length is 4.
Example 2:
Input: arr = ["cha","r","act","ers"]
Output: 6
Explanation: Possible longest valid concatenations are "chaers" ("cha" + "ers") and "acters" ("act" + "ers").
Example 3:
Input: arr = ["abcdefghijklmnopqrstuvwxyz"] Output: 26 Explanation: The only string in arr has all 26 characters.
Constraints:
1 <= arr.length <= 161 <= arr[i].length <= 26arr[i] contains only lowercase English letters.class Solution {
public:
int maxLength(vector<string>& A) {
vector<bitset<26>> dp = {bitset<26>()};
int res = 0;
for (auto& s : A) {
bitset<26> a;
for (char c : s)
a.set(c - 'a');
int n = a.count();
if (n < s.size()) continue;
for (int i = dp.size() - 1; i >= 0; --i) {
bitset c = dp[i];
if ((c & a).any()) continue;
dp.push_back(c | a);
res = max(res, (int)c.count() + n);
}
}
return res;
}
};