Update 3SumZero.cpp

Reduced code size.

Author: Sahil

Two-Pointers/3SumZero.cpp

@@ -1,70 +1,106 @@
-// https://www.interviewbit.com/problems/3-sum-zero/
-
 vector<vector<int> > Solution::threeSum(vector<int> &A) {
-    // Do not write main() function.
-    // Do not read input, instead use the arguments to the function.
-    // Do not print the output, instead return values as specified
-    // Still have a doubt. Checkout www.interviewbit.com/pages/sample_codes/ for more details
+    vector<vector<int> > v;
+    
+    if(A.size() == 0)return v;
 
-    vector<vector<int> > sol;
+    vector<pair<int, int> > v1(A.size());
 
-    if(A.size() < 2){
-        return sol;
+    for(int i = 0; i < A.size(); i++){
+        v1[i] = {A[i], i};
     }
 
-    sort(A.begin(), A.end());
+    sort(v1.begin(), v1.end());
 
-    int i = 0;
+    set<vector<int> > mp;
 
-    while(i < A.size()-2){
+    for(int i = 0; i < A.size(); i++){
+        int firset = v1[i].first;
         int j = i+1;
         int k = A.size()-1;
-        LOOP:while(j < k){
-            int sum = A[i] + A[j] + A[k];
-            if(sum == 0){
-                vector<int> temp;
-                temp.push_back(A[i]);
-                temp.push_back(A[j]);
-                temp.push_back(A[k]);
-                sol.push_back(temp);
-                temp.erase(temp.begin(),temp.end());
-                while(A[j] == A[j+1]){
-                    j++;
-                    if(j == A.size()){
-                        break;
-                    }
-                }
-                j++;                
-            }
-            else if(sum > 0){
-                while(A[k] == A[k-1]){
-                    k--;
-                    if(k == 0){
-                        break;
-                    }
-                }
-                k--;
-            }
-            else{
-                while(A[j] == A[j+1]){
-                    j++;
-                    if(j == A.size()){
-                        break;
-                    }
+        while(j < k){
+            if(v1[j].first + v1[k].first + firset  == 0){
+                vector<int> v2({A[v1[i].second], A[v1[j].second], A[v1[k].second]});
+                sort(v2.begin(), v2.end());
+                if(mp.find(v2) == mp.end()){
+                    v.push_back(v2);
+                    mp.insert(v2);
                 }
+                j++; k--;
+            }else if(v1[j].first + v1[k].first + firset  < 0){
                 j++;
-            }
-            
-        }
-        while(A[i+1] == A[i]){
-            i++;
-            if(i == A.size()-1){
-                return sol;
-            }
+            }else k--;
         }
-        i++;
     }
+    return v;
+}
+
+// // https://www.interviewbit.com/problems/3-sum-zero/
+
+// vector<vector<int> > Solution::threeSum(vector<int> &A) {
+//     // Do not write main() function.
+//     // Do not read input, instead use the arguments to the function.
+//     // Do not print the output, instead return values as specified
+//     // Still have a doubt. Checkout www.interviewbit.com/pages/sample_codes/ for more details
 
-    return sol;
+//     vector<vector<int> > sol;
 
-}
+//     if(A.size() < 2){
+//         return sol;
+//     }
+    
+//     sort(A.begin(), A.end());
+    
+//     int i = 0;
+    
+//     while(i < A.size()-2){
+//         int j = i+1;
+//         int k = A.size()-1;
+//         LOOP:while(j < k){
+//             int sum = A[i] + A[j] + A[k];
+//             if(sum == 0){
+//                 vector<int> temp;
+//                 temp.push_back(A[i]);
+//                 temp.push_back(A[j]);
+//                 temp.push_back(A[k]);
+//                 sol.push_back(temp);
+//                 temp.erase(temp.begin(),temp.end());
+//                 while(A[j] == A[j+1]){
+//                     j++;
+//                     if(j == A.size()){
+//                         break;
+//                     }
+//                 }
+//                 j++;                
+//             }
+//             else if(sum > 0){
+//                 while(A[k] == A[k-1]){
+//                     k--;
+//                     if(k == 0){
+//                         break;
+//                     }
+//                 }
+//                 k--;
+//             }
+//             else{
+//                 while(A[j] == A[j+1]){
+//                     j++;
+//                     if(j == A.size()){
+//                         break;
+//                     }
+//                 }
+//                 j++;
+//             }
+            
+//         }
+//         while(A[i+1] == A[i]){
+//             i++;
+//             if(i == A.size()-1){
+//                 return sol;
+//             }
+//         }
+//         i++;
+//     }
+    
+//     return sol;
+    
+// }