LeetCode 38. Count and Say

题目

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.

思路

好几题没刷leetcode手痒痒，又没太多时间，就选了个Easy的题啦…这个题目确实挺简单的，统计一下前面是不是重复就行了。在句末加一个特殊符号可以避免多写几行代码的样子~

代码

class Solution {
public:
    string countAndSay(int n) {
        string nStr = "1$";
        string nextStr = "";
        while(n > 1){
            char lastChr = '$';
            int lastCount = 0;
            for(int i=0; i<nStr.size(); i++){
                if(nStr[i] == lastChr){
                    lastCount++;
                } else {
                    if(lastCount > 0){
                        string tempStr;
                        while(lastCount > 0){
                            tempStr += (lastCount%10 +'0');
                            lastCount /= 10;
                        }
                        reverse(tempStr.begin(), tempStr.end());
                        nextStr += tempStr;
                        nextStr += lastChr;
                    }
                    lastCount = 1;
                    lastChr = nStr[i];
                }
            }
            nStr = nextStr + "$";
            nextStr = "";
            n--;
        }
        return nStr.substr(0, nStr.size()-1);
    }
};