前缀树java静态实现

class Trie {
    private static final int MAXN = 150001;
    private int[][] tree;
    private int[] end, pass;
    private int cnt;

    public Trie() {
        tree = new int[MAXN][26];
        end = new int[MAXN];
        pass = new int[MAXN];
        cnt = 1;
    }

    public void insert(String word) {
        int cur = 1;
        pass[cur]++;
        for (int i = 0, path; i < word.length(); i++) {
            path = word.charAt(i) - 'a';
            if (tree[cur][path] == 0) {
                tree[cur][path] = ++cnt;
            }
            cur = tree[cur][path];
            pass[cur]++;
        }
        end[cur]++;
    }

    public boolean search(String word) {
        int cur = 1;
        for (int i = 0, path; i < word.length(); i++) {
            path = word.charAt(i) - 'a';
            if (tree[cur][path] == 0) {
                return false;
            }
            cur = tree[cur][path];
        }
        return end[cur] > 0;
    }

    public boolean startsWith(String prefix) {
        int cur = 1;
        for (int i = 0, path; i < prefix.length(); i++) {
            path = prefix.charAt(i) - 'a';
            if (tree[cur][path] == 0) {
                return false;
            }
            cur = tree[cur][path];
        }
        return pass[cur] > 0;
    }

    public void delete(String word) {
		if (search(word)) {
			int cur = 1;
			pass[cur]--;
			for (int i = 0, path; i < word.length(); i++) {
				path = word.charAt(i) - 'a';
				if (--pass[tree[cur][path]] == 0) {
					tree[cur][path] = 0;
					return;
				}
				cur = tree[cur][path];
			}
			end[cur]--;
		}
	}

    public void clear() {
        for (int i = 0; i < MAXN; i++) {
            Arrays.fill(tree[i], 0);
            end[i] = 0;
            pass[i] = 0;
        }
        cnt = 1;
    }
}