文章目录
一、题目
6. 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
题目来源: leetcode
二、题解
找到字符串的周期规律,构建对应的字符串数组,
cpp
class Solution {
public:
string convert(string s, int numRows) {
int n = s.length();
if(numRows == 1) return s;
int reminder = 2 * numRows - 2;
vector<string> rowString(numRows,"");
for(int i = 0;i < n;i++){
int mod = i % reminder;
if(mod < numRows - 1) rowString[mod] += s[i];
else rowString[numRows - 1 - (mod - numRows + 1)] += s[i];
}
string res = "";
for(int i = 0;i < numRows;i++){
res += rowString[i];
}
return res;
}
};