[LeetCode] 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

解题思路是对字符串的逐个字母以Z字形方式标注行数和列数，然后再根据行数输出字符就行了

struct Index {
	Index(int _x, int _y) : x(_x), y(_y) {}
	int x, y;	
};

class Solution {
public:
	string convert(string s, int numRows) {
		if (numRows == 1)
			return s;
		int r = -1;
		int c = 0;
		int count = 0;
		int symbol = 0; // 0表示向下，1表示斜向上 
		vector store;
		while (count != s.length()) {
			if (r == 0) symbol = 0;
			if (r == numRows - 1) symbol = 1;
			if (symbol == 0) {
				r = r + 1;
				Index temp(r, c);
				store.push_back(temp);
			} else {
				r = r - 1;
				c = c + 1;
				Index temp(r, c);
				store.push_back(temp);
			}
			count++;
		}
		string result = "";
		for (int i = 0; i < numRows; i++) {
			for (int j = 0; j < store.size(); j++) {
				if (store[j].x == i)
					result.push_back(s[j]);
			}
		}
		return result;
	}
};