LeetCode——Count and Say

最新推荐文章于 2025-08-04 20:35:07 发布

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本文介绍了一种名为“计数读数”(Count and Say)的整数序列生成方法，并提供了一个C++实现示例。该序列从1开始，后续每一项都是前一项的描述。例如，1被描述为“一个1”，即11；11被描述为“两个1”，即21。文章详细解释了序列的生成规则，并展示了如何通过编程来生成任意第n项。

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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.

» Solve this problem

模拟。

class Solution {
public:
    string countAndSay(int n) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        string s = "1";
        string next;
        if (n == 1) {
            return s;
        }
        
        for (int i = 1, j; i < n; i++) {
            j = 0;
            while (j < s.size()) {
                int k = j + 1;
                while (k < s.size() && s[k] == s[j]) {
                    k++;
                }
                next += (k - j + '0');
                next += s[j];
                j = k;
            }
            s = next;
            next = "";
        }
        return s;
    }
};