easy map java two pointer 2441

Given an integer array nums that does not contain any zeros, find the largest positive integer k such that -k also exists in the array.

Return the positive integer k. If there is no such integer, return -1.

 

Example 1:

Input: nums = [-1,2,-3,3]
Output: 3
Explanation: 3 is the only valid k we can find in the array.
Example 2:

Input: nums = [-1,10,6,7,-7,1]
Output: 7
Explanation: Both 1 and 7 have their corresponding negative values in the array. 7 has a larger value.
Example 3:

Input: nums = [-10,8,6,7,-2,-3]
Output: -1
Explanation: There is no a single valid k, we return -1.
 

Constraints:

1 <= nums.length <= 1000
-1000 <= nums[i] <= 1000
nums[i] != 0

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Topics
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Hint 1
What data structure can help you to determine if an element exists?
Hint 2
Would a hash table help?

Author: Gauranshgoel123

largest-positive-integer-that-exists-with-its-negative.java

@@ -0,0 +1,41 @@
+class Solution {
+    public int findMaxK(int[] nums) {
+        int[] map=new int[1001];
+        int max=-1;
+        for(int i:nums){
+            if(i<0)
+                map[-i]=i;
+        }
+        for(int i : nums){
+            if(i>0 && map[i]!=0) 
+                 max=Math.max(max,i);
+        }
+        return max;
+    }
+}
+
+// Less opitimised solution beats 68%
+// class Solution {
+//     public int findMaxK(int[] nums) {
+//         Arrays.sort(nums);
+//         int left=0;
+//         int right=nums.length-1;
+//         int maxk=0;
+//         while(left<right){
+//             int sum=nums[left]+nums[right];
+//             if(sum==0){
+//                 maxk=Math.max(maxk,nums[right]);
+//                 left++;
+//                 right--;
+//             }
+//             else if(sum<0){
+//                 left++;
+//             }
+//             else right--;
+//         }
+//         if(maxk!=0){
+//             return maxk;
+//         }
+//         else return -1;
+//     }
+// }