Today I have done leetcode's February LeetCoding Challenge with cpp.

February LeetCoding Challenge 3

Description

Zigzag Conversion

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);

Example 1:

Input: s = "PAYPALISHIRING", numRows = 3
Output: "PAHNAPLSIIGYIR"

Example 2:

Input: s = "PAYPALISHIRING", numRows = 4
Output: "PINALSIGYAHRPI"
Explanation:
P     I    N
A   L S  I G
Y A   H R
P     I

Example 3:

Input: s = "A", numRows = 1
Output: "A"

Constraints:

1 <= s.length <= 1000
s consists of English letters (lower-case and upper-case), ',' and '.'.
1 <= numRows <= 1000

Solution

auto speedup = [](){
  cin.tie(nullptr);
  cout.tie(nullptr);
  ios::sync_with_stdio(false);
  return 0;
}();
class Solution {
public:
  string convert(string s, int numRows) {
    if(numRows == 1) return s;
    int len = s.length();
    string answer;
    for(int row = 0; row < numRows; ++row) {
      for(int pos = row; pos < len; pos += 2 * numRows - 2) {
        answer.push_back(s[pos]);
        if(!row || row == numRows - 1) continue;

        if(pos + 2 * (numRows - row - 1) < len) {
          answer.push_back(s[pos + 2 * (numRows - row - 1)]);
        }
      }
    }
    return answer;
  }
};

// Accepted
// 1157/1157 cases passed (15 ms)
// Your runtime beats 41.89 % of cpp submissions
// Your memory usage beats 65.47 % of cpp submissions (8.3 MB)

2023-02-03 Daily Challenge

February LeetCoding Challenge 3

Description

Solution