又做了一些

threeSum.cpp

@@ -7,25 +7,57 @@ using namespace std;
 class Solution
 {
 public:
-    vector<vector<int>> threeSum(vector<int> &nums)
+    vector<vector<int>> threeSum(std::vector<int> &nums)
     {
+        vector<int> zeros, positives, negatives;
+        set<vector<int>> result;
 
-        sort(nums.begin(), nums.end());
-        set<vector<int>> res;
+        // 划分元素
+        for (int num : nums) {
+            if (num == 0) {
+                zeros.push_back(num);
+            } else if (num > 0) {
+                positives.push_back(num);
+            } else {
+                negatives.push_back(num);
+            }
+        }
 
-        for(int i = 0; i < nums.size(); i++) {
-            for(int j = i + 1; j < nums.size(); j++) {
-                for(int k = nums.size() - 1; k > j ; k--) {
-                    if(nums[i] + nums[j] + nums[k] == 0) {
-                        vector<int> tmp = {nums[i], nums[j], nums[k]};
-                        res.insert(tmp);
-                    }
-                    
+        // 排序正数和负数
+        std::sort(positives.begin(), positives.end());
+        std::sort(negatives.begin(), negatives.end());
+
+        if (zeros.size() != 0) {
+            if (zeros.size() >= 3) {
+                result.insert({0, 0, 0});
+            }
+            for (int positive : positives) {
+                if (std::binary_search(negatives.begin(), negatives.end(), -positive)) {
+                    result.insert({-positive, 0, positive});
                 }
             }
         }
 
-        return vector<vector<int>>(res.begin(), res.end());
+        //正正负
+        for(int i = 0; i < positives.size(); i++) {
+            for(int j = i + 1; j < positives.size(); j++) {
+                if(std::binary_search(negatives.begin(), negatives.end(), -(positives[i] + positives[j]))){
+                    result.insert({-(positives[i] + positives[j]), positives[i], positives[j]});
+                }
+            }
+        }
+
+        //负负正
+        for(int i = 0; i < negatives.size(); i++) {
+            for(int j = i + 1; j < negatives.size(); j++) {
+                if (std::binary_search(positives.begin(), positives.end(), -(negatives[i] + negatives[j]))) {
+                    result.insert({negatives[i], negatives[j], -(negatives[i] + negatives[j])});
+                } 
+            }
+        }
+
+
+        return vector<vector<int>>(result.begin(), result.end());
     }
 };
 
@@ -34,8 +66,8 @@ int main()
     Solution s;
     vector<int> nums = {-1, 0, 1, 2, -1, -4};
     vector<vector<int>> res = s.threeSum(nums);
-    for(auto &v : res) {
-        for(auto &i : v) {
+    for (auto &v : res) {
+        for (auto &i : v) {
             cout << i << " ";
         }
         cout << endl;