Added zigZagConversion.cpp

Author: Anupam-Panwar

Strings/zigZagConversion.cpp

@@ -0,0 +1,71 @@
+/*
+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 s, int numRows)
+
+Input: s = "PAYPALISHIRING", numRows = 3
+Output: "PAHNAPLSIIGYIR"
+
+Constraints:
+ 1 <= s.length <= 1000
+ s consists of English letters (lower-case and upper-case), ',' and '.'.
+ 1 <= numRows <= 1000
+
+*/
+
+/*
+Time Complexity: O(N), where N is the length of the array
+Space Complexity: O(N), where N is the length of the array
+*/
+
+#include <bits/stdc++.h>
+using namespace std;
+
+string convert(string s, int numRows)
+{
+    vector<vector<char>> a(numRows); // vector of vector to store character in each rows
+    int i = 0; // variable to determine in which row we must add particular character
+    bool direction = true; // variable to determine the direction of movement
+    for (char ch : s)
+    {
+        a[i].push_back(ch);
+        if (direction == true) // if direction is down => increment i
+            i++;
+        if (i == numRows) // if i reached end => reverse the direction and decrement i
+        {
+            direction = false;
+            i--;
+        }
+        if (direction == false) // if direction is up => decrement i
+            i--;
+        if (i <= 0) // if i reached start => reverse the direction and set i to 0
+        {
+            direction = true;
+            i = 0;
+        }
+    }
+
+    string str = ""; // forming the final string to return
+    for (vector<char> c : a)
+    {
+        for (char ch : c)
+            str += ch;
+    }
+    return str;
+}
+
+int main() // driver function
+{
+    string str = "PAYPALISHIRING";
+    string ans = convert(str,3);
+    cout << ans;
+    return 0;
+}