class Solution {

public:

string convert(string s, int numRows) {

int len = s.length();

if(len <= 1 || numRows <=1) return s;

string as;

for(int i = 1; i <= numRows; ++i) {

int start = i - 1;

int now = start;

as += s[now];

int step1 = (numRows -1) * 2 - (i - 1) * 2;

int step2 = (numRows -1) * 2 - step1;

if(step1 == 0 && step2 == 0) continue;

while(true) {

if(now + step1 < len) {

now += step1;

if(step1 != 0) {

as += s[now];

}

} else {

break;

}

if(now + step2 < len) {

now += step2;

if(step2 != 0) {

as += s[now];

}

} else {

break;

}

}

}

return as;

}

};

why the response is "

Input: "AB", 3

Output: "AB"

Expected: "AB"

"