LeetCode Count and Say

最新推荐文章于 2019-08-14 16:27:56 发布

aay.zhang

最新推荐文章于 2019-08-14 16:27:56 发布

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本文详细解析了CountAndSay序列的生成过程，通过实例演示如何从输入整数n生成对应的序列。从序列定义出发，逐步推导生成算法的核心逻辑，并通过代码实现展示其应用。

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Count and Say

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

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

Solution:

class Solution {
public:
    string countAndSay(int n) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        string result="1";
        while(--n>0){
            string next;
            char last=result[0];
            int count=1;
            for(int i=1;i<result.length();++i){
                if(result[i]!=last){
                    next.push_back(count+'0');
                    next.push_back(last);
                    last=result[i];
                    count=1;
                }else{
                    ++count;
                }
            }
            if(count){
                next.push_back(count+'0');
                next.push_back(last);
            }
            result=next;
        }
        return result;
    }
};