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en/codes/cpp/chapter_backtracking/permutations_i.cpp
54 строки
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Yudong Jin
Translate all code to English (#1836)
31 дек 2025, 02:44
Не верифицирован
31 дек 2025, 02:44
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/** * File: permutations_i.cpp * Created Time: 2023-04-24 * Author: krahets (krahets@163.com) */ #include "../utils/common.hpp" /* Backtracking algorithm: Permutations I */ void backtrack(vector<int> &state, const vector<int> &choices, vector<bool> &selected, vector<vector<int>> &res) { // When the state length equals the number of elements, record the solution if (state.size() == choices.size()) { res.push_back(state); return; } // Traverse all choices for (int i = 0; i < choices.size(); i++) { int choice = choices[i]; // Pruning: do not allow repeated selection of elements if (!selected[i]) { // Attempt: make choice, update state selected[i] = true; state.push_back(choice); // Proceed to the next round of selection backtrack(state, choices, selected, res); // Backtrack: undo choice, restore to previous state selected[i] = false; state.pop_back(); } } } /* Permutations I */ vector<vector<int>> permutationsI(vector<int> nums) { vector<int> state; vector<bool> selected(nums.size(), false); vector<vector<int>> res; backtrack(state, nums, selected, res); return res; } /* Driver Code */ int main() { vector<int> nums = {1, 2, 3}; vector<vector<int>> res = permutationsI(nums); cout << "Input array nums = "; printVector(nums); cout << "All permutations res = "; printVectorMatrix(res); return 0; }