leetcode

Author: ayoubzulfiqar

README.md

@@ -202,6 +202,7 @@ This repo contain leetcode solution using DART and GO programming language. Most
 - [**1626.** Best Team With No Conflicts](BestTeamWithNoConflicts/best_team_with_no_conflicts.dart)
 - [**1071.** Greatest Common Divisor of Strings](GreatestCommonDivisorOfStrings/greatest_common_divisor_of_strings.dart)
 - [**953.** Verifying an Alien Dictionary](VerifyingAnAlienDictionary/verifying_an_alien_dictionary.dart)
+- [**6.** Zigzag Conversion](ZigzagConversion/zigzag_conversion.dart)
 
 ## Reach me via
 

ZigzagConversion/zigzag_conversion.dart

@@ -0,0 +1,64 @@
+/*
+
+
+-* 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 s, int numRows);
+ 
+
+Example 1:
+
+Input: s = "PAYPALISHIRING", numRows = 3
+Output: "PAHNAPLSIIGYIR"
+Example 2:
+
+Input: s = "PAYPALISHIRING", numRows = 4
+Output: "PINALSIGYAHRPI"
+Explanation:
+P     I    N
+A   L S  I G
+Y A   H R
+P     I
+Example 3:
+
+Input: s = "A", numRows = 1
+Output: "A"
+ 
+
+Constraints:
+
+1 <= s.length <= 1000
+s consists of English letters (lower-case and upper-case), ',' and '.'.
+1 <= numRows <= 1000
+
+*/
+class A {
+  String convert(String s, int numRows) {
+    if (numRows == 1) return s;
+    List<String> rows = List.filled(numRows, "");
+    int j = 0, d = 1;
+    for (int i = 0; i < s.length; i++) {
+      rows[j] += s[i];
+      if (j == numRows - 1)
+        d = -1;
+      else if (j == 0) d = 1;
+      j += d;
+    }
+
+    String res = "";
+    for (int i = 0; i < numRows; i++) {
+      res += rows[i];
+    }
+
+    return res;
+  }
+}

ZigzagConversion/zigzag_conversion.go

@@ -0,0 +1,26 @@
+package main
+
+import "bytes"
+
+func convert(s string, numRows int) string {
+	if numRows == 1 {
+		return s
+	}
+	rows := make([][]byte, numRows)
+	curRow, step := 0, 1
+	for i := range s {
+		rows[curRow] = append(rows[curRow], s[i])
+		curRow += step
+		if curRow == 0 {
+			step = 1
+		} else if curRow == numRows-1 {
+			step = -1
+		}
+	}
+
+	var res bytes.Buffer
+	for i := range rows {
+		res.Write(rows[i])
+	}
+	return res.String()
+}