ZigZag Conversion (Easy)

Description

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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".

Analysis

Easy部分的最后一题了。还有几题是要购买才能做的= =。做了一天。
easy部分除了购买部分一共39题。明天开始做medium部分了。
这题。。我是找规律的= =。sad。

My Solution

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//C++
class Solution {
public:
    string convert(string s, int nRows) {
        string ans;
        int len = s.length();
        if(nRows>=len||nRows<=1)
            return s;
        int n = 2*nRows-2;
        for(int i = 1,j = 1;i<=nRows;j=++i){
            if(i==1||i==nRows){
                while(j<=len){
                    ans+=s[j-1];
                    j+=n;
                }
            }
            else{
                int x = n-2*(i-1);
                int y = 2*(i-1);
                while(j<=len){
                    ans+=s[j-1];
                    j+=x;
                    if(j<=len)
                        ans+=s[j-1];
                    j+=y;
                }
            }
        }
        return ans;
    }
};