LeetCode--6


6. ZigZag Conversion


題目概述


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 text, int nRows);

convert(“PAYPALISHIRING”, 3) should return “PAHNAPLSIIGYIR”.

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解題思路


題目意思是給定一個字符串和行數,鋸齒形排列字母最後一行一行的輸出。例題的字符鋸齒形排列如下:


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


  1. 聲明一個含有numRows的string;

  2. 先向下走numRows步,再向上走numRows步,直至結束。


代碼實現


class Solution {
public:
string convert(string s, int numRows) {
if(numRows<=1) return s;//原字符串
string *str = new string[numRows];//含有numRows的string
int row = 0, step = 1;
for (int i = 0; i < (int)s.length(); ++i){
str[row].push_back(s[i]);
if (row == 0) step = 1;//向下走
else if (row == numRows - 1) step = -1;//向上走
row += step;
}
s.clear();
for (int j = 0; j < numRows; ++j){
s.append(str[j]);//生成一個字符串
}
delete[] str;
return s;
}
};

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