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| 1 | +/// Leetcode 380. Insert Delete GetRandom O(1) |
| 2 | +/// https://leetcode.com/problems/insert-delete-getrandom-o1/description/ |
| 3 | +/// |
| 4 | +/// 使用380号问题测试我们的代码 |
| 5 | +/// 该版本代码用于测试非递归实现的TrieMap |
| 6 | + |
| 7 | +import java.util.Random; |
| 8 | +import java.util.Stack; |
| 9 | +import java.util.TreeMap; |
| 10 | +import java.util.ArrayList; |
| 11 | +import java.util.Random; |
| 12 | + |
| 13 | +public class RandomizedSet_Trie { |
| 14 | + |
| 15 | + private class TrieMap { |
| 16 | + |
| 17 | + private class Node{ |
| 18 | + |
| 19 | + public boolean isWord; |
| 20 | + public TreeMap<Character, Node> next; |
| 21 | + public int val; |
| 22 | + |
| 23 | + public Node(boolean isWord, int val){ |
| 24 | + this.isWord = isWord; |
| 25 | + next = new TreeMap<>(); |
| 26 | + this.val = val; |
| 27 | + } |
| 28 | + |
| 29 | + public Node(){ |
| 30 | + this(false, -1); |
| 31 | + } |
| 32 | + } |
| 33 | + |
| 34 | + private Node root; |
| 35 | + private int size; |
| 36 | + |
| 37 | + public TrieMap(){ |
| 38 | + root = new Node(); |
| 39 | + size = 0; |
| 40 | + } |
| 41 | + |
| 42 | + // 获得Trie中存储的单词数量 |
| 43 | + public int getSize(){ |
| 44 | + return size; |
| 45 | + } |
| 46 | + |
| 47 | + // 向Trie中添加一个新的单词word |
| 48 | + public void add(String word, int val){ |
| 49 | + |
| 50 | + Node cur = root; |
| 51 | + for(int i = 0 ; i < word.length() ; i ++){ |
| 52 | + char c = word.charAt(i); |
| 53 | + if(cur.next.get(c) == null) |
| 54 | + cur.next.put(c, new Node()); |
| 55 | + cur = cur.next.get(c); |
| 56 | + } |
| 57 | + |
| 58 | + if(!cur.isWord){ |
| 59 | + cur.isWord = true; |
| 60 | + size ++; |
| 61 | + } |
| 62 | + cur.val = val; |
| 63 | + } |
| 64 | + |
| 65 | + // 查询单词word是否在Trie中 |
| 66 | + public boolean contains(String word){ |
| 67 | + |
| 68 | + Node cur = root; |
| 69 | + for(int i = 0 ; i < word.length() ; i ++){ |
| 70 | + char c = word.charAt(i); |
| 71 | + if(cur.next.get(c) == null) |
| 72 | + return false; |
| 73 | + cur = cur.next.get(c); |
| 74 | + } |
| 75 | + return cur.isWord; |
| 76 | + } |
| 77 | + |
| 78 | + // 查询单词word所对应的值 |
| 79 | + public int get(String word){ |
| 80 | + |
| 81 | + Node cur = root; |
| 82 | + for(int i = 0 ; i < word.length() ; i ++){ |
| 83 | + char c = word.charAt(i); |
| 84 | + if(cur.next.get(c) == null) |
| 85 | + throw new RuntimeException("Can not get"); |
| 86 | + cur = cur.next.get(c); |
| 87 | + } |
| 88 | + return cur.val; |
| 89 | + } |
| 90 | + |
| 91 | + // 删除word, 返回是否删除成功 |
| 92 | + public boolean remove(String word){ |
| 93 | + |
| 94 | + Stack<Node> stack = new Stack<>(); |
| 95 | + stack.push(root); |
| 96 | + for(int i = 0; i < word.length(); i ++){ |
| 97 | + if(!stack.peek().next.containsKey(word.charAt(i))) |
| 98 | + return false; |
| 99 | + stack.push(stack.peek().next.get(word.charAt(i))); |
| 100 | + } |
| 101 | + |
| 102 | + if(!stack.peek().isWord) |
| 103 | + return false; |
| 104 | + |
| 105 | + // 将该单词结尾isWord置空 |
| 106 | + stack.peek().isWord = false; |
| 107 | + size --; |
| 108 | + |
| 109 | + // 如果单词最后一个字母的节点的next非空, |
| 110 | + // 说明trie中还存储了其他以该单词为前缀的单词,直接返回 |
| 111 | + if(stack.peek().next.size() > 0) |
| 112 | + return true; |
| 113 | + else |
| 114 | + stack.pop(); |
| 115 | + |
| 116 | + // 自底向上删除 |
| 117 | + for(int i = word.length() - 1; i >= 0; i --){ |
| 118 | + stack.peek().next.remove(word.charAt(i)); |
| 119 | + // 如果上一个节点的isWord为true,或者是其他单词的前缀,则直接返回 |
| 120 | + if(stack.peek().isWord || stack.peek().next.size() > 0) |
| 121 | + return true; |
| 122 | + } |
| 123 | + return true; |
| 124 | + } |
| 125 | + } |
| 126 | + |
| 127 | + TrieMap map; |
| 128 | + ArrayList<Integer> nums; |
| 129 | + |
| 130 | + /** Initialize your data structure here. */ |
| 131 | + public RandomizedSet_Trie() { |
| 132 | + map = new TrieMap(); |
| 133 | + nums = new ArrayList<>(); |
| 134 | + } |
| 135 | + |
| 136 | + /** Inserts a value to the set. Returns true if the set did not already contain the specified element. */ |
| 137 | + public boolean insert(int val) { |
| 138 | + |
| 139 | + String key = Integer.toString(val); |
| 140 | + if(map.contains(key)) |
| 141 | + return false; |
| 142 | + |
| 143 | + nums.add(val); |
| 144 | + int index = nums.size() - 1; |
| 145 | + map.add(key, index); |
| 146 | + return true; |
| 147 | + } |
| 148 | + |
| 149 | + /** Removes a value from the set. Returns true if the set contained the specified element. */ |
| 150 | + public boolean remove(int val) { |
| 151 | + |
| 152 | + String key = Integer.toString(val); |
| 153 | + if(!map.contains(key)) |
| 154 | + return false; |
| 155 | + |
| 156 | + int index = map.get(key); |
| 157 | + map.remove(key); |
| 158 | + |
| 159 | + int num = nums.get(nums.size() - 1); |
| 160 | + nums.remove(nums.size() - 1); |
| 161 | + |
| 162 | + if(num != val) { |
| 163 | + nums.set(index, num); |
| 164 | + map.add(Integer.toString(num), index); |
| 165 | + } |
| 166 | + |
| 167 | + return true; |
| 168 | + } |
| 169 | + |
| 170 | + /** Get a random element from the set. */ |
| 171 | + public int getRandom() { |
| 172 | + |
| 173 | + Random random = new Random(); |
| 174 | + int index = random.nextInt(nums.size()); |
| 175 | + return nums.get(index); |
| 176 | + } |
| 177 | + |
| 178 | + public static void main(String[] args){ |
| 179 | + |
| 180 | + RandomizedSet_TrieR rs = new RandomizedSet_TrieR(); |
| 181 | + rs.insert(0); |
| 182 | + rs.remove(0); |
| 183 | + rs.insert(-1); |
| 184 | + rs.remove(0); |
| 185 | + } |
| 186 | +} |
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