【C++】【LeetCode】38. Count and Say

题目

The count-and-say sequence is the sequence of integers with the first five terms as following:

1. 1
2. 11
3. 21
4. 1211
5. 111221

1 is read off as “one 1” or 11.
11 is read off as “two 1s” or 21.
21 is read off as “one 2, then one 1” or 1211.
Given an integer n, generate the nth term of the count-and-say sequence.
Note: Each term of the sequence of integers will be represented as a string.
Example 1:

Input: 1
Output: “1”
Example 2:

Input: 4
Output: “1211”

思路

依次计算string中相同的数字，然后组成新的string，没什么难度。

代码

class Solution {
public:
    string countAndSay(int n) {
        string preStr = "";
        string curStr = "";
        for (int i = 1; i <= n; i++) {
            if (i == 1) {
                preStr = "1";
                continue;
            } else {
                int count = 1;
                for (int j = 0; j < preStr.size(); j++) {
                    if (j != preStr.size()-1 && preStr[j] == preStr[j+1]) {
                        count++;
                    } else {
                        curStr += to_string(count) + preStr[j];
                        count = 1;
                    }
                }
            }
            preStr = curStr;
            curStr = "";
        }
        return preStr;
    }
};