53 lines
1.3 KiB
C++
53 lines
1.3 KiB
C++
#include <queue>
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#include <string>
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#include <vector>
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class Solution {
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public:
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int openLock(const std::vector<std::string> &deadends,
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const std::string &target) {
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std::vector<bool> visited(10000);
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for (const auto &end : deadends) {
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visited[std::stoi(end)] = true;
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}
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// we're already starting with a dead end
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if (visited[0]) {
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return -1;
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}
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auto t = std::stoi(target);
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std::queue<std::pair<int, int>> q;
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q.emplace(0, 0);
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visited[0] = true;
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while (!q.empty()) {
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auto [steps, comb] = q.front();
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q.pop();
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// found the target
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if (comb == t) {
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return steps;
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}
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auto comb_tmp = comb;
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for (auto d = 1; d < 10000; d *= 10) {
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auto digit = comb_tmp % 10;
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comb_tmp /= 10;
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for (auto i : {-1, 1}) {
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auto next_digit = (digit + i + 10) % 10;
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auto next_comb = comb + (next_digit - digit) * d;
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if (!visited[next_comb]) {
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q.emplace(steps + 1, next_comb);
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visited[next_comb] = true;
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}
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}
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}
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}
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return -1;
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}
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};
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