75 lines
2.2 KiB
C++
75 lines
2.2 KiB
C++
#include <iostream>
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#include <vector>
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std::vector<int> get_next_vector(const std::string& s) {
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std::vector<int> next(s.size() + 1);
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next[0] = -1;
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for (int i = 0; i < next.size() - 1; i++) { // 实际上写入下一位
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int j = next[i];
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while (j != -1 && s[i] != s[j]) { // j = -1: 完全不匹配，s[i]==s[j]: 直接能用
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j = next[j];
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}
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if (j == -1 || s[i] == s[j]) { j++; }
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next[i + 1] = j;
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}
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return next;
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}
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std::vector<int> get_optimized_next_vector(const std::string& s, const std::vector<int>& next) {
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std::vector<int> next_optimized(next.size());
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next_optimized[0] = -1;
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next_optimized[next.size() - 1] = next[next.size() - 1];
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for (int i = 1; i < next.size() - 1; i++) {
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if (s[next[i]] == s[i]) {
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next_optimized[i] = next_optimized[next[i]];
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} else {
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next_optimized[i] = next[i];
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}
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}
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return next_optimized;
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}
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std::vector<int> find_substring_pos(const std::string& target, const std::string& pattern) {
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std::vector<int> matched_pos;
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const std::vector<int> next_vector = get_optimized_next_vector(pattern, get_next_vector(pattern));
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int j = 0;
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for (int i = 0; i < target.size(); i++) {
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while (j > -1 && target[i] != pattern[j]) {
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j = next_vector[j];
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}
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if (j == -1) {
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j = 0; // 完全失配，直接 i++ j++
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continue;
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}
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if (target[i] == pattern[j]) { j++; }
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if (j == pattern.size()) {
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matched_pos.push_back(i - static_cast<int>(pattern.size()) + 1);
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j = next_vector[j];
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}
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}
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return matched_pos;
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}
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std::ostream& operator<<(std::ostream& os, std::vector<int> vec) {
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for (const auto& elem : vec) {
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os << elem << " ";
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}
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return os;
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}
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int main() {
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std::ios::sync_with_stdio(false);
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std::cin.tie(nullptr);
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std::string target, pattern;
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std::cin >> target >> pattern;
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std::clog << get_next_vector(pattern) << std::endl;
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std::clog << get_optimized_next_vector(pattern, get_next_vector(pattern)) << std::endl;
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for (const auto i : find_substring_pos(target, pattern)) {
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std::cout << i << " ";
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}
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std::cout << std::endl;
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return 0;
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}
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