[leetcode] count-and-say

时间限制：1秒 空间限制：32768K 热度指数：3439

本题知识点：  字符串  leetcode

 算法知识视频讲解

题目描述

The count-and-say sequence is the sequence of integers beginning as follows:
1, 11, 21, 1211, 111221, ...

1is read off as"one 1"or11.
11is read off as"two 1s"or21.
21is read off as"one 2, thenone 1"or1211.

Given an integer n, generate the n th sequence.

Note: The sequence of integers will be represented as a string.

题解：

 1 #include<string>
 2 #include<iostream>
 3 #include<sstream>
 4 #include<vector>
 5 using namespace std;
 6 
 7 class Solution {
 8 public:
 9     string countAndSay(int n) {
10         vector<int> arr;
11         vector<int> temp;
12         int cnt = n - 1;
13         arr.push_back(1);
14         while (cnt-- > 0) {
15             temp.clear();
16             int count = 1;
17             for (int i = 1; i < arr.size(); i++) {
18                 if (arr[i] == arr[i - 1]) {
19                     count++;
20                 }
21                 else {
22                     temp.push_back(count);
23                     temp.push_back(arr[i - 1]);
24                     count = 1;
25                 }
26             }
27             temp.push_back(count);
28             temp.push_back(arr[arr.size() - 1]);
29             arr = temp;
30         }
31         ostringstream oss;
32         for (int i = 0; i < arr.size(); i++) {
33             oss << arr[i];
34         }
35         return oss.str();
36     }
37 };