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"
.
程序很简单第一排和最后一排是一组公式,2*nRows-2,,其他排用另一组公式,分奇偶,公式分别是2 * (nRows - i - 1)和2 * i 。时间:29ms
代码如下:
class Solution { public: string convert(string s, int nRows) { if (nRows <= 1 || s.size() == 0) return s; string str; for (int i = 0; i < s.size() && i < nRows; i++){ int j = i, x=1; while (j < s.size()){ str += s[j]; if (i == 0 || i == nRows-1) j += 2 * nRows - 2; else{ if (x & 0x1) j += 2 * (nRows - i - 1); else j += 2 * i; x++; } } } return str; } };
“If you give someone a program, you will frustrate them for a day; if you teach them how to program, you will frustrate them for a lifetime.”