P1481

cpp
#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

struct TrieNode {
    TrieNode* children[26];
    int depth;

    TrieNode() {
        for (int i = 0; i < 26; i++) {
            children[i] = nullptr;
        }
        depth = 0;
    }
};

int findLongestWordChain(vector<string>& words) {
    sort(words.begin(), words.end());
    TrieNode* root = new TrieNode();
    int maxLength = 0;

    for (const string& word : words) {
        TrieNode* cur = root;
        int length = 0;

        for (char c : word) {
            int index = c - 'a';
            if (cur->children[index] == nullptr) {
                cur->children[index] = new TrieNode();
            }
            cur = cur->children[index];
            length = max(length, cur->depth);
        }

        cur->depth = length + 1;
        maxLength = max(maxLength, cur->depth);
    }

    return maxLength;
}

int main() {
    int n;
    cin >> n;

    vector<string> words;
    for (int i = 0; i < n; i++) {
        string word;
        cin >> word;
        words.push_back(word);
    }

    int result = findLongestWordChain(words);
    cout << result << endl;

    return 0;
}

解法二 dp

cpp
#include <iostream>
#include <vector>
#include <string>
using namespace std;

int findLongestWordChain(vector<string> words) {
    int n = words.size();
    vector<int> dp(n, 1);

    for (int i = 1; i < n; i++) {
        for (int j = 0; j < i; j++) {
            if (words[i].find(words[j]) == 0) {
                dp[i] = max(dp[i], dp[j] + 1);
            }
        }
    }

    int maxChainLength = 0;
    for (int i = 0; i < n; i++) {
        maxChainLength = max(maxChainLength, dp[i]);
    }

    return maxChainLength;
}

int main() {
    int n;
    cin >> n;
    vector<string> words(n);

    for (int i = 0; i < n; i++) {
        cin >> words[i];
    }

    sort(words.begin(), words.end()); // Sort the words lexicographically

    int result = findLongestWordChain(words);
    cout << result << endl;

    return 0;
}