[leetcode] 6. ZigZag Conversion 解题报告

题目链接：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)

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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思路：看了半天才把题目看懂，原来就是走个之字形。举个栗子：abcdefghijklmn 4

a g m

b f h l n

c e i k

d j

然后我们要给出的答案就是agmbfhinceikdj，横着读。

思路就是有几行就申请几个字符串，然后一个字符串把一行的字符收集起来，最后再加在一起。关于之字形遍历我们可以设置一个递增标记flag，可以为1和-1，代表下一个是增加还是减小。

今天最后一题，早上五点了，该睡觉了，还有5题就把easy题刷完了，马上就120了，马上假期就结束了，开学之前看能不能到150。晚安了！也可以说早安了！




代码如下：

class Solution {
public:
string convert(string s, int numRows) {
if(numRows == 1) return s;
vector<string> vec(numRows);
int flag = 1, k =0;
for(int i =0; i< s.size(); i++)
{
vec[k].append(1, s[i]);
if(flag == 1 && k == numRows-1) flag = -1;
else if(flag == -1 && k == 0) flag = 1;
k += flag;
}
string result;
for(auto val: vec) result += val;
return result;
}
};