The string “PAYPALISHIRING” is written in a zigzag pattern on a given number of rows like this: (you may want to display this pattern in a fixed font for better legibility)

• P A H N
• A P L S I I G
• Y I R
  And then read line by line: “PAHNAPLSIIGYIR” Write the code that will take a string and make this conversion given a number of rows:
  string convert(string s, int numRows);

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Solution 1

C++

class Solution {
public:
    string convert(string s, int numRows) {
        if(numRows==1) return s;
        string ans;
        for(int i=0;i<numRows;i++){
            int step=(numRows-1)*2;
            int substep=step-i*2;
            int j=i;
            while(j<s.size()){
                ans.push_back(s[j]);
                j+=substep;
                if(j>=s.size()) break;
                if(substep!=0 && substep!=step) ans.push_back(s[j]);
                j+=step-substep;
            }
        }
        return ans;
    }
};