You are given a string s
, a split is called good if you can split s
into 2 non-empty strings p
and q
where its concatenation is equal to s
and the number of distinct letters in p
and q
are the same.
Return the number of good splits you can make in s
.
Example 1:
Input: s = "aacaba"
Output: 2
Explanation: There are 5 ways to split "aacaba"
and 2 of them are good.
("a", "acaba") Left string and right string contains 1 and 3 different letters respectively.
("aa", "caba") Left string and right string contains 1 and 3 different letters respectively.
("aac", "aba") Left string and right string contains 2 and 2 different letters respectively (good split).
("aaca", "ba") Left string and right string contains 2 and 2 different letters respectively (good split).
("aacab", "a") Left string and right string contains 3 and 1 different letters respectively.
Example 2:
Input: s = "abcd" Output: 1 Explanation: Split the string as follows ("ab", "cd").
Example 3:
Input: s = "aaaaa" Output: 4 Explanation: All possible splits are good.
Example 4:
Input: s = "acbadbaada" Output: 2
Constraints:
s
contains only lowercase English letters.1 <= s.length <= 10^5
A:
就是用了2个map 然后比较大小
class Solution { public: int numSplits(string s) { int n = s.length(); unordered_map<char,int> Left, Right; for(int i =0;i<n;i++) Right[s[i]] += 1; int res = 0; for(int i = 0;i< n-1; i++){ char ch = s[i]; Left[ch]+=1; Right[ch] -= 1; if(Right[ch] == 0) Right.erase(ch); if(Left.size() == Right.size()) res++; } return res; } };
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