[LeetCode] 830. 较大分组的位置

一题多解

// 解法一
class Solution {
public:
    vector<vector<int>> largeGroupPositions(string s) {
        vector<vector<int>> ans;
        int i,j;
        for(i=0;i<s.length();i++){
            for(j=i+1;j<s.length();){
                if(s[i]==s[j])  j++;
                else  break;
            }
            if(j-i>=3)  ans.push_back({i,j-1});
            i=j-1;
        }
        return ans;
    }
};

//解法二
class Solution {
public:
    vector<vector<int>> largeGroupPositions(string s) {
        vector<vector<int>> res;

        for (int i = 1, j = 0; i < s.size(); ++i) {
            while (i < s.size() &&  s[i] == s[j]) ++i;
            if ( i - j >= 3) res.push_back({j, i - 1});
            j = i;
        }
        
        return res;
            
    }
};

解法三
class Solution {
public:
    vector<vector<int>> largeGroupPositions(string s) {
        vector<vector<int>> res;
        int n=s.size();
        int left=0,right=0;
        while(right<n)
        {
            int cnt=0;
            while(s[left]==s[right])
            {
                right++;
                cnt++;
            }
            if(cnt>=3)res.push_back({left,right-1});
            left=right;
        }
        if(res.size()==0)return {};
        return res;
    }
};