/*
1. transform to lower case
2. parsing the string
3. if not banned, insert into map and the counter of the key ++
4. look the max counter in the map.
*/
class Solution {
public:
string mostCommonWord(string paragraph, vector<string>& banned) {
string ret;
map<string, int> mp;
map<string, int> mp_ban;
for (string s : banned) mp_ban[s]++;
//std::transform(s.begin(), s.end(), s.begin(),
// [](unsigned char c) { return std::toupper(c); });
std::transform(paragraph.begin(), paragraph.end(), paragraph.begin(), [](unsigned char c) {return tolower(c);});
//transform(paragraph.begin(),paragraph.end(),::tolower);
for (int i = 0; i<paragraph.size();i++)
{
int j = i;
//while (paragraph[j]>'z' && paragraph[j]<'a') j++;
while ((paragraph[j]>'z' || paragraph[j]<'a') && j<paragraph.size()) j++;
i = j;
while (paragraph[i] >= 'a' && paragraph[i] <= 'z' && i<paragraph.size()) i++;
string str = paragraph.substr(j, i - j);
if (!mp_ban.count(str))
mp[str]++;
}
int max_num = 0;
for (auto kv : mp)
{
if (kv.second > max_num)
{
max_num = kv.second;
ret = kv.first;
}
}
return ret;
}
};