64 lines
1.3 KiB
C++
64 lines
1.3 KiB
C++
#include <vector>
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#include <string>
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#include <iostream>
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#include <functional>
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/**
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* 269. Alien Dictionary
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*
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* Description is unavailable.
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*/
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class Solution {
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public:
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static std::string alienOrder(const std::vector<std::string>& words) {
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bool G[26][26]{{}}, present[26]{};
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for (int i = 1; i < words.size(); ++i) {
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const std::string& x = words[i - 1];
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const std::string& y = words[i];
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const int k = std::min(x.length(), y.length());
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int j = 0;
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for (; j < k; ++j) {
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if (x[j] == y[j])
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continue;
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G[x[j] - 'a'][y[j] - 'a'] = true;
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std::printf("%c > %c\n", x[j], y[j]);
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break;
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}
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if (j == k && y.length() < x.length())
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return "";
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}
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for (const auto& x : words)
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for (const char c : x)
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present[c - 'a'] = true;
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char tp[26]{}, c[26]{};
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int t = 26;
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std::function<bool(int)> dfs = [&](int x) {
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c[x] = -1;
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for (int i = 0; i < 26; ++i) {
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if (!present[i] || !G[x][i])
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continue;
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if (c[i] < 0 || (!c[i] && !dfs(i)))
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return false;
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}
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c[x] = 1;
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tp[--t] = x + 'a';
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return true;
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};
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for (int i = 0; i < 26; ++i)
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if (present[i] && !c[i] && !dfs(i))
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return "";
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for (int i = 0; i < 26; ++i)
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if (present[i] && !c[i])
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tp[--t] = i + 'a';
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return {tp + t, tp + 26};
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}
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};
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int main() {
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std::cout << Solution::alienOrder({"ab", "adc"});
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return 0;
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}
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