## ZigZag Conversion

06/23/2016 String

## Question

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".

## Solution

Result: Accepted Time: 8ms

It’s easy to solve.

char* convert(char* s, int numRows) {
int len = strlen(s);
int i,idx,cnt=0,da,db;
if(numRows < 2)
return s;
char * str = malloc(sizeof(char) * (len + 5));
for(i = 1; i <= numRows ; i++)
{
idx = i-1;
str[cnt++] = s[idx ];
da = 2*(numRows - i);
db = 2*(i-1);
while(idx < len)
{
idx += da;
if(i!= numRows && idx < len)
str[cnt++] = s[idx ];
idx += db;
if( i!=1 && idx < len)
str[cnt++] = s[idx];
}
}
str[cnt] = 0;
return str;
}


Complexity Analytics

• Time Complexity: $O(n)$
• Space Complexity: $O(n)$