ZigZag Conversion 解法

ZigZag Conversion 解法

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第四周题目
难度：Media
LeetCode题号：6

题目

Description：

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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思考

声明numRows个string，用于保存每行的字符
逐个遍历原字符串，同时维护一个index，表示第 index 行
通过一个变量flag，判断index是要加加，还是减减，即向下扫还是向上扫

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代码

class Solution {
public:
    string convert(string s, int numRows) {
        if (numRows == 1) {
            return s;
        }

        string row[numRows] = {""};
        bool flag = true;
        int index = 0;

        for (int i = 0; i < s.length(); i++) {
            row[index] += s[i];
            flag ? index++:index--;
            if (index == 0) {
                flag = true;
            }
            if (index == numRows - 1) {
                flag = false;
            }
        }

        string result = "";
        for (int i = 0; i < numRows; i++) {
            result += row[i];
        }

        return result;
    }
};