LeetCode题解(6)--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 text, int nRows);

convert("PAYPALISHIRING", 3) should return "PAHNAPLSIIGYIR".

 思路：

把字符串先用二维矩阵存下来，然后先行后列存储到新string即可。注意Z形稀疏矩阵可以压缩存储，使空间复制度还是O（n）。AC代码如下：

class Solution {
public:
    string convert(string s, int numRows) {
        if(s==""|| numRows==1){
            return s;
        }
        int residual,i_col,n=s.size();
        int circle=2*numRows-2,count=0;
        int col=(n-1)/(numRows-1)+1;
        char tmp[numRows][col];
        string res;
        memset(tmp, 0, sizeof(tmp));
        for(int i=0;i<n;i++){
            residual=i%circle;
            i_col=2*(i/circle)+(i%circle)/numRows;
            if(residual<numRows)
                tmp[residual][i_col]=s[i];
            else
                tmp[numRows-residual%numRows-2][i_col]=s[i];
        }
        for(int i=0;i<numRows;i++)
            for(int j=0;j<col;j++)
                if(tmp[i][j]!='')
                    res+=tmp[i][j];
        return res;
    }
};