算法-String

6. ZigZag ConversionThe 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".Solution:
public String convert(String s, int nRows) {
    char[] c = s.toCharArray();
    int len = c.length;
    StringBuffer[] sb = new StringBuffer[nRows];
    for (int i = 0; i < sb.length; i++) sb[i] = new StringBuffer();
    
    int i = 0;
    while (i < len) {
        for (int idx = 0; idx < nRows && i < len; idx++) // vertically down
            sb[idx].append(c[i++]);
        for (int idx = nRows-2; idx >= 1 && i < len; idx--) // obliquely up
            sb[idx].append(c[i++]);
    }
    for (int idx = 1; idx < sb.length; idx++)
        sb[0].append(sb[idx]);
    return sb[0].toString();
}
题目只给了一个例子,对zigzag没有理解明白。看了答案才知道怎么一回事。

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