two-pointers-1

ContainerWater.java

@@ -0,0 +1,17 @@
+public class ContainerWater {
+    public int containerWater(int[] nums) {
+        int left = 0;
+        int right = height.length-1;
+        int area = 0;
+        while (left<right) {
+            int currArea = (right-left) * Math.min(height[left],height[right]);
+            area = Math.max(area,currArea);
+            if (height[left] >height[right]) {
+                right--;
+            } else {
+                left++;
+            }
+        }
+        return area;
+    }
+}

SortColor.java

@@ -0,0 +1,24 @@
+public class SortColor {
+    public void sortColor(int[] nums) {
+        int left = 0;
+        int i=0;
+        int right = nums.length-1;
+        while (i<=right){
+            if (nums[i] == 2) {
+                swap(nums, i, right);
+                right--;
+            } else if (nums[i] == 0) {
+                swap(nums, i, left);
+                left++;
+                i++;
+            } else {
+                i++;
+            }
+        }
+    }
+    public void swap(int[] nums, int left, int right) {
+        int temp = nums[left];
+        nums[left] = nums[right];
+        nums[right] = temp;
+    }
+}

ThreeSum.java

@@ -0,0 +1,32 @@
+import java.util.*;
+
+public class ThreeSum {
+    public List<List<Integer>> threeSum(int[] nums) {
+        List<List<Integer>> ans = new ArrayList<>();
+        Arrays.sort(nums);
+        for (int i=0; i<nums.length-2; i++){
+            //outside duplicacy
+            if (i >0 && nums[i] == nums[i-1]) continue;
+            int left =i+1;
+            int right = nums.length-1;
+
+            while(left<right) {
+
+                int sum = nums[i] + nums[left] + nums[right];
+                if (sum == 0) {
+                    List<Integer> triple = Arrays.asList(nums[i],nums[left],nums[right]);
+                    ans.add(triple);
+                    left++;
+                    right--;
+                    while (left<right && nums[left] == nums[left-1]) left++;
+                    while (left<right && nums[right] == nums[right+1]) right--;
+                } else if (sum >0) {
+                    right--;
+                } else {
+                    left++;
+                }
+            }
+        }
+        return ans;
+    }
+}

TwoSum.java

@@ -0,0 +1,15 @@
+import java.util.*;
+
+public class TwoSum {
+    public int[] twoSum(int[] nums, int target) {
+        HashMap<Integer, Integer> hm = new HashMap<>();
+        for (int i=0; i<nums.length; i++){
+            int diff = target - nums[i];
+            if (hm.containsKey(diff)) {
+                return new int[]{hm.get(diff), i};
+            }
+            hm.put(nums[i], i);
+        }
+        return null;
+    }
+}