830. Positions of Large Groups

问题：

给定字符串，返回连续相同字符子串长度>=3的始终位置集合。

Example 1:
Input: "abbxxxxzzy"
Output: [[3,6]]
Explanation: "xxxx" is the single large group with starting  3 and ending positions 6.

Example 2:
Input: "abc"
Output: []
Explanation: We have "a","b" and "c" but no large group.

Example 3:
Input: "abcdddeeeeaabbbcd"
Output: [[3,5],[6,9],[12,14]]

　　

解法：

参考代码：

class Solution {
public:
    vector<vector<int>> largeGroupPositions(string S) {
        vector<vector<int>> res;
        int count=0;
        int i;
        char curc;
        for(i=0; i<S.length(); i++){
            if(curc!=S[i]) {
                if(count>=3){
                    res.push_back({i-count, i-1});
                }
                curc = S[i];
                count=0;
            }
            count++;
        }
        if(count>=3){
            res.push_back({i-count, i-1});
        }
        return res;
    }
};