题目描述：

In a string S of lowercase letters, these letters form consecutive groups of the same character.

For example, a string like S = "abbxxxxzyy" has the groups "a", "bb", "xxxx", "z" and "yy".

Call a group large if it has 3 or more characters.  We would like the starting and ending positions of every large group.

The final answer should be in lexicographic order.

 

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]]

 

Note:  1 <= S.length <= 1000

 

要完成的函数：

vector<vector<int>> largeGroupPositions(string S) 

 

说明：

1、给定一个字符串S，如果一个字符连续出现三次及三次以上，那么它就是一个“大组合”，要求找出所有“大组合”的起始位置和结束位置，最终以vector<vector<int>>的形式返回。

2、明白题意，这又是一道简单题。

直接贴上代码（附详解），如下：

vector
     
      
       > largeGroupPositions(string S)     {        int s1=S.size(),i=0,j;        vector
       
        
         >res;//最后返回的vector        vector
         
          res1;//子vector        while(i
         
        
       
      
     

上述代码实测13ms，因为服务器接收到的cpp submissions有限，所以没有打败的百分比。