leetcode6-z字形变换

class  {
public:
    string convert(string s, int numRows) {
        int i = 0, j;
        string result;
        vector<string> output(numRows);
        while(i < s.length()){
            for(j = 0; j < numRows && i < s.length(); j++){
                output[j] += s[i++];
            }
            for(j = numRows - 2; j > 0 && i < s.length(); j--){//输出Z中间的字符
                output[j] += s[i++];
            }
        }
        for(i = 0; i < numRows; i++)  //合并numRows个数组
            result += output[i];
        return result;
    }
};