Problem
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Given a string, find the length of the longest substring T that contains at most 2 distinct characters.For example, Given s = “
eceba”,T is "
ece" which its length is 3.
Solution
采用雙指針的思想落萎，beg和end悯许，每次end向右滑動(dòng)一格仆嗦，然后用hash記錄字符數(shù)，如果當(dāng)前substring.size() <= 2則記錄先壕，否則beg向右滑動(dòng)一格瘩扼，更新hash直到substring.size <= 2為止。
class Solution {
public:
int lengthOfLongestSubstringTwoDistinct(string s) {
if (s.size() == 0) {
return 0;
}
int beg = 0;
int end = 0;
map<char, int> count;
int maxLen = INT_MIN;
for(int end = 0; end < s.size(); end++) {
count[s[end]]++;
while (count.size() > 2) {
if (count[s[beg]] == 1) {
count.erase(count.find(s[beg]));
} else {
count[s[beg]]--;
}
beg++;
}
maxLen = max(maxLen, end - beg + 1);
}
return maxLen;
}
};
