51 lines
1.3 KiB
C#
51 lines
1.3 KiB
C#
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public class Solution {
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private class Node {
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public Dictionary<char, Node> Next { get; set; } = new();
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public bool Has { get; set; } = false;
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public Node() { }
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}
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private static Node MakeTrie(string[] dictionary) {
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var root = new Node();
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foreach (var word in dictionary) {
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var node = root;
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foreach (var c in word) {
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if (!node.Next.ContainsKey(c)) {
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node.Next[c] = new();
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}
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node = node.Next[c];
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}
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node.Has = true;
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}
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return root;
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}
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public int MinExtraChar(string s, string[] dictionary) {
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var trie = MakeTrie(dictionary);
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var length = s.Length;
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var dp = new int[length + 1];
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for (var start = length - 1; start >= 0; --start) {
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dp[start] = 1 + dp[start + 1];
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var node = trie;
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for (var end = start; end < length; ++end) {
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if (!node.Next.ContainsKey(s[end])) {
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break;
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}
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node = node.Next[s[end]];
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if (node.Has) {
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dp[start] = Math.Min(dp[start], dp[end + 1]);
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}
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}
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}
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return dp[0];
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}
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}
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