Positions of Large Groups

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

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

 2         vector<vector<int>> res;

 3         for(int i = 0; i < S.length(); ){

 4             int j = i + 1;

 5             while(S[j] == S[i]){

 6                 j++;

 7             }

 8             if(j-i >= 3){

 9                 res.push_back({i,j-1});      //二维vector可直接插入vector

10             }

11             i = j;

12         }

13         return res;

14

15     }

注意点：二维vector插入的用法。

巴特西

Positions of Large Groups

Positions of Large Groups

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