Description

LINK: https://leetcode.com/problems/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)

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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:

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string convert(string s, int numRows);

Example 1:

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

Example 2:

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Input: s = "PAYPALISHIRING", numRows = 4
Output: "PINALSIGYAHRPI"
Explanation:

P     I    N
A   L S  I G
Y A   H R
P     I

Solution

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static auto _ = []()
{
    ios::sync_with_stdio(false);
    cin.tie();
    return nullptr;
}();

class Solution {
public:
    string convert(string s, int numRows) {
        if (numRows == 1) return s;
        int len = s.size();
        string rs(len, '#');
        int it = 0;
        int period = 2*numRows - 2;
        
        
        for (int i = 0; i < numRows; i++) {
            int skip = 2 * i;
            for (int j = i; j < len;){
                rs[it++] = s[j];
                if (skip != period)
                    skip = period - skip;
                j += skip;
            }
        }
        return rs;
    }
};

Discussion

非常简单的一道题