107 lines
2.4 KiB
Dart
107 lines
2.4 KiB
Dart
/**
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* File: space_complexity.dart
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* Created Time: 2023-2-12
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* Author: Jefferson (JeffersonHuang77@gmail.com)
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*/
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// ignore_for_file: unused_local_variable
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import 'dart:collection';
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import '../utils/list_node.dart';
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import '../utils/print_util.dart';
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import '../utils/tree_node.dart';
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/* Function */
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int function() {
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// Perform some operations
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return 0;
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}
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/* Constant complexity */
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void constant(int n) {
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// Constants, variables, objects occupy O(1) space
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final int a = 0;
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int b = 0;
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List<int> nums = List.filled(10000, 0);
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ListNode node = ListNode(0);
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// Variables in a loop occupy O(1) space
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for (var i = 0; i < n; i++) {
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int c = 0;
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}
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// Functions in a loop occupy O(1) space
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for (var i = 0; i < n; i++) {
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function();
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}
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}
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/* Linear complexity */
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void linear(int n) {
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// Array of length n occupies O(n) space
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List<int> nums = List.filled(n, 0);
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// A list of length n occupies O(n) space
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List<ListNode> nodes = [];
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for (var i = 0; i < n; i++) {
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nodes.add(ListNode(i));
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}
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// A hash table of length n occupies O(n) space
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Map<int, String> map = HashMap();
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for (var i = 0; i < n; i++) {
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map.putIfAbsent(i, () => i.toString());
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}
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}
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/* Linear complexity (recursive implementation) */
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void linearRecur(int n) {
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print('递归 n = $n');
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if (n == 1) return;
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linearRecur(n - 1);
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}
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/* Quadratic complexity */
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void quadratic(int n) {
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// Matrix occupies O(n^2) space
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List<List<int>> numMatrix = List.generate(n, (_) => List.filled(n, 0));
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// A two-dimensional list occupies O(n^2) space
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List<List<int>> numList = [];
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for (var i = 0; i < n; i++) {
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List<int> tmp = [];
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for (int j = 0; j < n; j++) {
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tmp.add(0);
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}
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numList.add(tmp);
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}
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}
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/* Quadratic complexity (recursive implementation) */
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int quadraticRecur(int n) {
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if (n <= 0) return 0;
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List<int> nums = List.filled(n, 0);
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print('递归 n = $n 中的 nums 长度 = ${nums.length}');
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return quadraticRecur(n - 1);
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}
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/* Exponential complexity (building a full binary tree) */
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TreeNode? buildTree(int n) {
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if (n == 0) return null;
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TreeNode root = TreeNode(0);
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root.left = buildTree(n - 1);
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root.right = buildTree(n - 1);
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return root;
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}
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/* Driver Code */
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void main() {
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int n = 5;
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// Constant complexity
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constant(n);
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// Linear complexity
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linear(n);
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linearRecur(n);
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// Quadratic complexity
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quadratic(n);
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quadraticRecur(n);
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// Exponential complexity
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TreeNode? root = buildTree(n);
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printTree(root);
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}
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