From c2fe62dcfb5a607ed5ecd53b9364d44d5237368b Mon Sep 17 00:00:00 2001
From: Hriday-A <hriday.agarwal20103@gmail.com>
Date: Sat, 25 Apr 2026 00:05:02 -0500
Subject: [PATCH] Completed Two-Pointers-1 Assignment

---
 3sum.java                 | 30 ++++++++++++++++++++++++++++++
 container_most_water.java | 24 ++++++++++++++++++++++++
 sort_colors.java          | 29 +++++++++++++++++++++++++++++
 3 files changed, 83 insertions(+)
 create mode 100644 3sum.java
 create mode 100644 container_most_water.java
 create mode 100644 sort_colors.java

diff --git a/3sum.java b/3sum.java
new file mode 100644
index 00000000..e159ec7d
--- /dev/null
+++ b/3sum.java
@@ -0,0 +1,30 @@
+// Time Complexity : O(n^2)
+// Space Complexity : O(1)
+// Did this code successfully run on Leetcode : Yes
+// Explaination : We use a two-pointer approach after sorting the array to find all unique triplets that sum to zero.
+
+class Solution {
+    public List<List<Integer>> threeSum(int[] nums) {
+        Arrays.sort(nums);
+        int n = nums.length;
+        List<List<Integer>> result = new ArrayList<>();
+        for(int i=0;i<n;i++){
+            if(i!=0 && nums[i]==nums[i-1]) continue;
+            if(nums[i]>0) break;
+            int low=i+1, high= n-1;
+            while(low<high){
+                int sum = nums[i]+nums[low]+nums[high];
+                if(sum==0){
+                    result.add(Arrays.asList(nums[i],nums[low],nums[high]));
+                    low++;
+                    high--;
+                    while(low<high && nums[low]==nums[low-1]) low++;
+                    while(low<high && nums[high]==nums[high+1]) high--;
+                }
+                else if(sum>0) high--;
+                else low++; 
+            }
+        }
+        return result;
+    }
+}
\ No newline at end of file
diff --git a/container_most_water.java b/container_most_water.java
new file mode 100644
index 00000000..b46aee0e
--- /dev/null
+++ b/container_most_water.java
@@ -0,0 +1,24 @@
+// Time Complexity : O(n)
+// Space Complexity : O(1)
+// Did this code successfully run on Leetcode : yes 
+// Explaination : We use two pointers to calculate the area and 
+// move the pointer with smaller height to find the maximum area.
+class Solution {
+    public int maxArea(int[] height) {
+        int n = height.length;
+        int l =0;
+        int r = n-1;
+        int max=0;
+        while(l<r){
+            int curr = Math.min(height[l],height[r]);
+            int area = curr*(r-l);
+            max= Math.max(max,area);
+            if(height[l]<=height[r]){
+                l++;
+            }else{
+                r--;
+            }
+        }
+        return max;
+    }
+}
\ No newline at end of file
diff --git a/sort_colors.java b/sort_colors.java
new file mode 100644
index 00000000..33068dbe
--- /dev/null
+++ b/sort_colors.java
@@ -0,0 +1,29 @@
+// Time Complexity : O(n)
+// Space Complexity : O(1)
+// Did this code successfully run on Leetcode : Yes
+// Explaination : We use three pointers to sort the array in-place.
+class Solution {
+    public void sortColors(int[] nums) {
+        int high = nums.length-1;
+        int low = 0;
+        int mid = 0;
+        while(mid<=high){
+            if(nums[mid]==2){
+                swap(nums,mid,high);
+                high--;
+            }else if(nums[mid]==0){
+                swap(nums,mid,low);
+                low++;
+                mid++;
+            }else mid++;
+            
+        }
+    }
+
+    private void swap(int[] nums, int m, int l){
+        int temp;
+        temp = nums[m];
+        nums[m]= nums[l];
+        nums[l]= temp;
+    }
+}
\ No newline at end of file