feat(src): add 46-permute, 47-permuteUnique

Author: kwu130

src/46-permute.cpp

@@ -0,0 +1,62 @@
+//
+// Created by 1412 on 2025/10/27.
+//
+
+#include <bits/stdc++.h>
+
+using namespace std;
+
+class Solution {
+public:
+    vector<vector<int>> permute(vector<int>& nums) {
+        vector<vector<int>> res;
+        dfs(nums, vector<bool>(nums.size(), false), {}, res);
+        return res;
+    }
+
+private:
+    void dfs(vector<int>& nums, vector<bool>&& used, vector<int>&& path, vector<vector<int>>& res) {
+        if (path.size() == nums.size()) {
+            res.emplace_back(path);
+            return;
+        }
+        for (int i = 0; i < nums.size(); ++i) {
+            if (used[i]) continue;
+            used[i] = true;
+            path.emplace_back(nums[i]);
+            dfs(nums, std::move(used), std::move(path), res);
+            path.pop_back();
+            used[i] = false;
+        }
+    }
+};
+
+void test() {
+    Solution s;
+    vector<int> nums = {1, 2, 3};
+    vector<vector<int>> expected = {
+        {1, 2, 3},
+        {1, 3, 2},
+        {2, 1, 3},
+        {2, 3, 1},
+        {3, 1, 2},
+        {3, 2, 1}
+    };
+    assert(s.permute(nums) == expected);
+
+    nums = {0, 1};
+    expected = {
+        {0, 1},
+        {1, 0}
+    };
+    assert(s.permute(nums) == expected);
+
+    nums = {1};
+    expected = {{1}};
+    assert(s.permute(nums) == expected);
+}
+
+int main() {
+    test();
+    return 0;
+}

src/47-permuteUnique.cpp

@@ -0,0 +1,61 @@
+//
+// Created by 1412 on 2025/10/27.
+//
+
+#include <bits/stdc++.h>
+
+using namespace std;
+
+class Solution {
+public:
+    vector<vector<int>> permuteUnique(vector<int>& nums) {
+        vector<vector<int>> res;
+        ranges::sort(nums);  // sort nums firstly
+        dfs(nums, vector<bool>(nums.size(), false), {}, res);
+        return res;
+    }
+
+private:
+    void dfs(vector<int>& nums, vector<bool>&& used, vector<int>&& path, vector<vector<int>>& res) {
+        if (path.size() == nums.size()) {
+            res.emplace_back(path);
+            return;
+        }
+        for (int i = 0; i < nums.size(); ++i) {
+            if (used[i]) continue;
+            if (i > 0 && nums[i] == nums[i - 1] && !used[i - 1]) continue;
+            used[i] = true;
+            path.emplace_back(nums[i]);
+            dfs(nums, std::move(used), std::move(path), res);
+            path.pop_back();
+            used[i] = false;
+        }
+    }
+};
+
+void test() {
+    Solution s;
+    vector<int> nums = {1, 1, 2};
+    vector<vector<int>> expected = {
+        {1, 1, 2},
+        {1, 2, 1},
+        {2, 1, 1}
+    };
+    assert(s.permuteUnique(nums) == expected);
+
+    nums = {1, 2, 3};
+    expected = {
+        {1, 2, 3},
+        {1, 3, 2},
+        {2, 1, 3},
+        {2, 3, 1},
+        {3, 1, 2},
+        {3, 2, 1}
+    };
+    assert(s.permuteUnique(nums) == expected);
+}
+
+int main() {
+    test();
+    return 0;
+}