Accepted

Author: gouthampradhan

problems/src/FourSum.java

@@ -0,0 +1,65 @@
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+/**
+ * Created by gouthamvidyapradhan on 29/03/2017.
+ * Accepted
+ */
+public class FourSum
+{
+
+    /**
+     * Main method
+     * @param args
+     * @throws Exception
+     */
+    public static void main(String[] args) throws Exception
+    {
+        int[] nums = {1, 0, -1, 0, -2, 2};
+        System.out.println(new FourSum().fourSum(nums, 0));
+    }
+
+    public List<List<Integer>> fourSum(int[] nums, int target)
+    {
+        List<List<Integer>> result = new ArrayList<>();
+        if(nums.length < 4) return result;
+        Arrays.sort(nums);
+        for(int i = 0; i < nums.length - 3; i++)
+        {
+            if(i == 0 || nums[i] != nums[i - 1])
+            {
+                for(int j = i + 1; j < nums.length - 2; j ++)
+                {
+                    if(j == i + 1 || nums[j] != nums[j - 1])
+                    {
+                        int k = j + 1, l = nums.length - 1;
+                        while(k < l)
+                        {
+                            if(k != j + 1 && nums[k] == nums[k + 1])
+                            {
+                                k++; continue;
+                            }
+                            int sum = nums[i] + nums[j] + nums[k] + nums[l];
+                            if(sum == target)
+                            {
+                                result.add(Arrays.asList(nums[i], nums[j], nums[k], nums[l]));
+                                k++; l --;
+                            }
+                            else if(sum < target)
+                            {
+                                k ++;
+                            }
+                            else
+                            {
+                                l --;
+                            }
+                        }
+                    }
+                }
+            }
+        }
+        return result;
+    }
+
+}

problems/src/ThreeSum.java

@@ -0,0 +1,52 @@
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+
+/**
+ * Created by gouthamvidyapradhan on 29/03/2017.
+ * Accepted
+ */
+public class ThreeSum
+{
+    /**
+     * Main method
+     * @param args
+     * @throws Exception
+     */
+    public static void main(String[] args) throws Exception
+    {
+        int[] nums = {-1,0,1,2,-1,-4,-1,0,1,2,-1,-4,-1,0,1,2,-1,-4,-1,0,1,2,-1,-4,-1,0,1,2,-1,-4,-1,0,1,2,-1,-4,-1,0,1,2,-1,-4,-1,0,1,2,-1,-4};
+        System.out.println(new ThreeSum().threeSum(nums));
+    }
+
+    public List<List<Integer>> threeSum(int[] nums)
+    {
+        List<List<Integer>> result = new ArrayList<>();
+        if(nums.length < 3) return result;
+        Arrays.sort(nums);
+        for(int i = 0, l = nums.length; i < l - 2; i ++)
+        {
+            if(i == 0 || nums[i] != nums[i - 1])
+            {
+                int j = i + 1, k = l - 1;
+                while(k > j)
+                {
+                    if(j != i + 1 && nums[j] == nums[j - 1])
+                    {
+                        j ++;
+                        continue;
+                    }
+                    int sum = nums[i] + nums[j] + nums[k];
+                    if(sum == 0)
+                    {
+                        result.add(Arrays.asList(nums[i], nums[j], nums[k]));
+                        k--; j++;
+                    }
+                    else if(sum > 0) k--;
+                    else j++;
+                }
+            }
+        }
+        return result;
+    }
+}