Change project structure to a Maven Java project + Refactor (#2816)

2025-12-19 07:00:35 +08:00 · 2021-11-12 07:59:36 +01:00
parent 8e533d2617
commit 9fb3364ccc
642 changed files with 26570 additions and 25488 deletions
--- a/src/main/java/com/thealgorithms/misc/ThreeSumProblem.java
+++ b/src/main/java/com/thealgorithms/misc/ThreeSumProblem.java
@@ -0,0 +1,102 @@
+package com.thealgorithms.misc;
+
+import java.util.*;
+
+public class ThreeSumProblem {
+
+    public static void main(String args[]) {
+        Scanner scan = new Scanner(System.in);
+        System.out.print("Enter the target sum ");
+        int ts = scan.nextInt();
+        System.out.print("Enter the number of elements in the array ");
+        int n = scan.nextInt();
+        System.out.println("Enter all your array elements:");
+        int arr[] = new int[n];
+        for (int i = 0; i < n; i++) {
+            arr[i] = scan.nextInt();
+        }
+        ThreeSumProblem th = new ThreeSumProblem();
+        System.out.println("Brute Force Approach\n" + (th.BruteForce(arr, ts)) + "\n");
+        System.out.println("Two Pointer Approach\n" + (th.TwoPointer(arr, ts)) + "\n");
+        System.out.println("Hashmap Approach\n" + (th.Hashmap(arr, ts)));
+
+    }
+
+    public List<List<Integer>> BruteForce(int[] nums, int target) {
+        List<List<Integer>> arr = new ArrayList<List<Integer>>();
+
+        for (int i = 0; i < nums.length; i++) {
+            for (int j = i + 1; j < nums.length; j++) {
+                for (int k = j + 1; k < nums.length; k++) {
+                    if (nums[i] + nums[j] + nums[k] == target) {
+                        List<Integer> temp = new ArrayList<>();
+                        temp.add(nums[i]);
+                        temp.add(nums[j]);
+                        temp.add(nums[k]);
+                        Collections.sort(temp);
+                        arr.add(temp);
+                    }
+
+                }
+            }
+        }
+        arr = new ArrayList<List<Integer>>(new LinkedHashSet<List<Integer>>(arr));
+        return arr;
+    }
+
+    public List<List<Integer>> TwoPointer(int[] nums, int target) {
+        Arrays.sort(nums);
+        List<List<Integer>> arr = new ArrayList<List<Integer>>();
+        int start = 0;
+        int end = 0;
+        int i = 0;
+        while (i < nums.length - 1) {
+            start = i + 1;
+            end = nums.length - 1;
+            while (start < end) {
+                if (nums[start] + nums[end] + nums[i] == target) {
+                    List<Integer> temp = new ArrayList<>();
+                    temp.add(nums[i]);
+                    temp.add(nums[start]);
+                    temp.add(nums[end]);
+                    arr.add(temp);
+                    start++;
+                    end--;
+                } else if (nums[start] + nums[end] + nums[i] < target) {
+                    start += 1;
+                } else {
+                    end -= 1;
+                }
+
+            }
+            i++;
+        }
+        Set<List<Integer>> set = new LinkedHashSet<List<Integer>>(arr);
+        return new ArrayList<List<Integer>>(set);
+    }
+
+    public List<List<Integer>> Hashmap(int[] nums, int target) {
+        Arrays.sort(nums);
+        Set<List<Integer>> ts = new HashSet();
+        HashMap<Integer, Integer> hm = new HashMap<>();
+
+        for (int i = 0; i < nums.length; i++) {
+            hm.put(nums[i], i);
+        }
+
+        for (int i = 0; i < nums.length; i++) {
+            for (int j = i + 1; j < nums.length; j++) {
+                int t = target - nums[i] - nums[j];
+                if (hm.containsKey(t) && hm.get(t) > j) {
+                    List<Integer> temp = new ArrayList<>();
+                    temp.add(nums[i]);
+                    temp.add(nums[j]);
+                    temp.add(t);
+                    ts.add(temp);
+                }
+            }
+        }
+        return new ArrayList(ts);
+    }
+
+}