leetcode

Author: ayoubzulfiqar

ConvertANumberToHexadecimal/convert_a_number_to_hexadecimal.dart

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+/*
+
+-* 405. Convert a Number to Hexadecimal *-
+
+Given an integer num, return a string representing its hexadecimal representation. For negative integers, two’s complement method is used.
+
+All the letters in the answer string should be lowercase characters, and there should not be any leading zeros in the answer except for the zero itself.
+
+Note: You are not allowed to use any built-in library method to directly solve this problem.
+
+ 
+
+Example 1:
+
+Input: num = 26
+Output: "1a"
+Example 2:
+
+Input: num = -1
+Output: "ffffffff"
+ 
+
+Constraints:
+
+-231 <= num <= 231 - 1
+
+
+*/
+String toHexString(int num) {
+  if (num == 0) {
+    return "0";
+  }
+
+  int n = num.toUnsigned(32);
+  final String ref = "0123456789abcdef";
+
+  String result = "";
+
+  while (n != 0) {
+    result = ref[n & 0xF] + result;
+    n >>= 4;
+  }
+
+  return result;
+}
+
+String toHex(int num) {
+  return (num < 0)
+      ? (num.toUnsigned(32)).toRadixString(16)
+      : num.toRadixString(16);
+}
+
+extension ToHex on int {
+  String toHexString(int num) {
+    if (num == 0) {
+      return "0";
+    }
+
+    int n = num.toUnsigned(32);
+    final String ref = "0123456789abcdef";
+
+    String result = "";
+
+    while (n != 0) {
+      result = ref[n & 0xF] + result;
+      n >>= 4;
+    }
+
+    return result;
+  }
+}

ConvertANumberToHexadecimal/convert_a_number_to_hexadecimal.go

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+package main
+
+func toHex(num int) string {
+	if num == 0 {
+		return "0"
+	}
+
+	const bitsPerDigit = 4
+	const mask = (1 << bitsPerDigit) - 1
+
+	hex := make([]byte, 8)
+	i := 7
+
+	// Convert negative numbers to their two's complement representation
+	if num < 0 {
+		num = (1 << 32) + num
+	}
+
+	for num != 0 {
+		nib := num & mask
+		hex[i] = getHexDigit(nib)
+		num >>= bitsPerDigit
+		i--
+	}
+
+	return string(hex[i+1:])
+}
+
+func getHexDigit(n int) byte {
+	if n < 10 {
+		return byte('0' + n)
+	}
+	return byte('a' + n - 10)
+}
+
+//--------------------------
+

ConvertANumberToHexadecimal/convert_a_number_to_hexadecimal.md

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+# 🔥 Number to Hex 🔥 || Simple Fast and Easy || with Explanation
+
+## Solution - 1
+
+```dart
+String toHex(int num) {
+  return (num < 0)
+      ? (num.toUnsigned(32)).toRadixString(16)
+      : num.toRadixString(16);
+}
+```
+
+### Extra - Avoid It (Not-Optimized)
+
+```dart
+extension ToHex on int {
+  String toHex() {
+    return (this < 0)
+        ? (this.toUnsigned(32)).toRadixString(16)
+        : this.toRadixString(16);
+  }
+}
+```
+
+## Solution - 2
+
+```dart
+String toHexString(int num) {
+  if (num == 0) {
+    return "0";
+  }
+
+  int n = num.toUnsigned(32);
+  final String ref = "0123456789abcdef";
+
+  String result = "";
+
+  while (n != 0) {
+    result = ref[n & 0xF] + result;
+    n >>= 4;
+  }
+
+  return result;
+}
+```
+
+### Extra (Optimized Version - BitManipulation)
+
+```dart
+extension ToHex on int {
+  String toHexString(int num) {
+    if (num == 0) {
+      return "0";
+    }
+
+    int n = num.toUnsigned(32);
+    final String ref = "0123456789abcdef";
+
+    String result = "";
+
+    while (n != 0) {
+      result = ref[n & 0xF] + result;
+      n >>= 4;
+    }
+
+    return result;
+  }
+}
+```
+
+### Bonus
+
+To Use on Any Number In Our case we can use only on int.
+But for bonus I have implemented for both double as well as int.
+InShort For NUM use can use DART Generics if you want but not recommended
+
+### [Source](https://github.com/ayoubzulfiqar/dart-utils/blob/main/extensions/to_hex.dart)
+
+### [GitHub](https://github.com/ayoubzulfiqar/leetcode)