Merge pull request #248 from akashgk/migrate

Migrate to Null Safety, Update Actions, Fix #176

Author: akashgk

.github/workflows/dart_test_analyze_format.yml

@@ -3,15 +3,13 @@ on: [push, pull_request]
 jobs:
   dart_test_analyze_format:
     runs-on: ubuntu-latest
-    container: google/dart
+    container:
+      image: google/dart
     steps:
       - uses: actions/checkout@v2
-      - run: (echo 'deb http://deb.debian.org/debian buster main contrib non-free') > /etc/apt/sources.list.d/buster.list
-      - run: apt-get update
-      - run: apt-get install --no-install-recommends -y -q lcov
+      # - run: (echo 'deb http://deb.debian.org/debian buster main contrib non-free') > /etc/apt/sources.list.d/buster.list
       - run: dart pub get
       - run: dart format --set-exit-if-changed .
       - run: dart test --coverage .
       - run: dart pub run coverage:format_coverage -i . -l > coverage.lcov
-      - run: lcov -l coverage.lcov
       - run: dart analyze

.gitignore

@@ -19,3 +19,4 @@ doc/api/
 *.js_
 *.js.deps
 *.js.map
+*.json

DIRECTORY.md

@@ -43,8 +43,6 @@
     * [Cycle In Linked List](https://github.com/TheAlgorithms/Dart/blob/master/data_structures/linked_list/cycle_in_linked_list.dart)
     * [Linked List](https://github.com/TheAlgorithms/Dart/blob/master/data_structures/linked_list/linked_list.dart)
     * [Merge Sorted List](https://github.com/TheAlgorithms/Dart/blob/master/data_structures/linked_list/merge_sorted_list.dart)
-  * Quad Tree
-    * [Quad Tree](https://github.com/TheAlgorithms/Dart/blob/master/data_structures/quad_tree/quad_tree.dart)
   * Queue
     * [Circular Queue](https://github.com/TheAlgorithms/Dart/blob/master/data_structures/Queue/Circular_Queue.dart)
     * [List Queue](https://github.com/TheAlgorithms/Dart/blob/master/data_structures/Queue/List_Queue.dart)

array/car_pool.dart

@@ -2,7 +2,7 @@
 // Solution Explanation: https://leetcode.com/problems/car-pooling/solutions/3252690/dart-time-o-n-o-1-space-solution/
 
 import 'dart:math';
-import 'package:test/test.dart';
+import "package:test/test.dart";
 
 bool carPooling(List<List<int>> trips, int capacity) {
   List<int> passengerTimelineCount = List.filled(1001, 0);

conversions/Decimal_To_Any.dart

@@ -48,9 +48,10 @@ String decimalToAny(int value, int base) {
   while (value > 0) {
     int remainder = value % base;
     value = value ~/ base;
-    output =
-        (remainder < 10 ? remainder.toString() : ALPHABET_VALUES[remainder]) +
-            output;
+    output = (remainder < 10
+            ? remainder.toString()
+            : ALPHABET_VALUES[remainder] ?? '0') +
+        output;
   }
 
   return negative ? '-' + output : output;

conversions/Decimal_to_Hexadecimal.dart

@@ -27,7 +27,7 @@ String decimal_to_hexadecimal(int decimal_val) {
     int remainder = decimal_val % 16;
     decimal_val = decimal_val ~/ 16;
     if (hex_table.containsKey(remainder.toString())) {
-      hex_val = hex_table[remainder.toString()];
+      hex_val = hex_table[remainder.toString()] ?? '';
     } else {
       hex_val = remainder.toString();
     }

conversions/Integer_To_Roman.dart

@@ -41,7 +41,7 @@ List<String> RomanNumbers = [
 
 List<String> integer_to_roman(int num) {
   if (num < 0) {
-    return null;
+    return [];
   }
 
   List<String> result = [];

conversions/binary_to_decimal.dart

@@ -4,7 +4,7 @@ import 'package:test/test.dart';
 
 int binaryToDecimal(String binaryString) {
   binaryString = binaryString.trim();
-  if (binaryString == null || binaryString == "") {
+  if (binaryString == "") {
     throw FormatException("An empty value was passed to the function");
   }
   bool isNegative = binaryString[0] == "-";
@@ -14,8 +14,8 @@ int binaryToDecimal(String binaryString) {
     if ("01".contains(binaryString[i]) == false) {
       throw FormatException("Non-binary value was passed to the function");
     } else {
-      decimalValue +=
-          pow(2, binaryString.length - i - 1) * int.parse((binaryString[i]));
+      decimalValue += (pow(2, binaryString.length - i - 1).toInt() *
+          (int.tryParse(binaryString[i]) ?? 0));
     }
   }
   return isNegative ? -1 * decimalValue : decimalValue;

conversions/binary_to_hexadecimal.dart

@@ -24,7 +24,7 @@ Map<String, String> hexTable = {
 String binaryToHexadecimal(String binaryString) {
   // checking for unexpected values
   binaryString = binaryString.trim();
-  if (binaryString == null || binaryString == "") {
+  if (binaryString.isEmpty) {
     throw new FormatException("An empty value was passed to the function");
   }
   try {
@@ -47,7 +47,7 @@ String binaryToHexadecimal(String binaryString) {
   int i = 0;
   while (i != binaryString.length) {
     String bin_curr = binaryString.substring(i, i + 4);
-    hexValue += hexTable[bin_curr];
+    hexValue += hexTable[bin_curr] ?? '';
     i += 4;
   }
 

conversions/binary_to_octal.dart

@@ -21,7 +21,7 @@ void main() {
 
 String binaryToOctal(String binaryString) {
   binaryString = binaryString.trim();
-  if (binaryString == null || binaryString == "") {
+  if (binaryString.isEmpty) {
     throw new FormatException("An empty value was passed to the function");
   }
   bool isNegative = binaryString[0] == "-";