solves next greater element I

Author: anishLearnsToCode

README.md

@@ -1,7 +1,7 @@
 # Leetcode Algorithms
 
-![problems-solved](https://img.shields.io/badge/Problems%20Solved-105/1412-1f425f.svg)
-![problems-solved-java](https://img.shields.io/badge/Java-99/1412-1abc9c.svg)
+![problems-solved](https://img.shields.io/badge/Problems%20Solved-106/1412-1f425f.svg)
+![problems-solved-java](https://img.shields.io/badge/Java-106/1412-1abc9c.svg)
 ![problems-solved-python](https://img.shields.io/badge/Python-16/1412-1abc9c.svg)
 [![PRs Welcome](https://img.shields.io/badge/PRs-welcome-brightgreen.svg)](CONTRIBUTING.md)
 
@@ -127,8 +127,8 @@
 | 476 | [Number Complement](https://leetcode.com/problems/number-complement) | Easy | [![Java](https://img.icons8.com/color/40/000000/java-coffee-cup-logo.png)](src/NumberComplement.java) |
 | 482 | [License Key Formatting](https://leetcode.com/problems/license-key-formatting) | Easy | [![Java](https://img.icons8.com/color/40/000000/java-coffee-cup-logo.png)](src/LicenseKeyFormatting.java) |
 | 485 | [Max Consecutive Ones](https://leetcode.com/problems/max-consecutive-ones) | Easy | [![Java](https://img.icons8.com/color/40/000000/java-coffee-cup-logo.png)](src/MaxConsecutiveOnes.java) |
-| 492 | [Construct the Rectangle](https://leetcode.com/problems/construct-the-rectangle) | Easy | [![Java](https://img.icons8.com/color/40/000000/java-coffee-cup-logo.png)](src/ConstructTheRectangle.java) [![Python](https://img.icons8.com/color/35/000000/python.png)](python/construct_the_rectangle.py)|
-| 496 | [Next Greater Element I](https://leetcode.com/problems/next-greater-element-i) | Easy | |
+| 492 | [Construct the Rectangle](https://leetcode.com/problems/construct-the-rectangle) | Easy | [![Java](https://img.icons8.com/color/40/000000/java-coffee-cup-logo.png)](src/ConstructTheRectangle.java) [![Python](https://img.icons8.com/color/35/000000/python.png)](python/construct_the_rectangle.py) |
+| 496 | [Next Greater Element I](https://leetcode.com/problems/next-greater-element-i) | Easy | [![Java](https://img.icons8.com/color/40/000000/java-coffee-cup-logo.png)](src/NextGreaterElementI.java) [![Python](https://img.icons8.com/color/35/000000/python.png)](python/next_greater_element_i.py) |
 | 500 | [Keyboard Row](https://leetcode.com/problems/keyboard-row) | Easy | |
 | 501 | [Find Mode in Binary Search Tree](https://leetcode.com/problems/find-mode-in-binary-search-tree) | Easy | |
 | 504 | [Base 7](https://leetcode.com/problems/base-7) | Easy | |

python/next_greater_element_i.py

@@ -0,0 +1,23 @@
+from typing import List, Dict
+
+
+class Solution:
+    def nextGreaterElement(self, nums1: List[int], nums2: List[int]) -> List[int]:
+        next_greater_map = self.get_next_greater_elements(nums2)
+        result = []
+        for element in nums1:
+            result.append(next_greater_map[element])
+        return result
+
+    def get_next_greater_elements(self, array: List[int]) -> Dict[int, int]:
+        stack = []
+        result = {}
+        for element in array:
+            while len(stack) != 0 and element > stack[-1]:
+                result[stack.pop()] = element
+            stack.append(element)
+
+        while len(stack) !=0:
+            result[stack.pop()] = -1
+
+        return result

src/NextGreaterElementI.java

@@ -0,0 +1,39 @@
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Stack;
+
+public class NextGreaterElementI {
+    public static int[] nextGreaterElement(int[] nums1, int[] nums2) {
+        Map<Integer, Integer> nextGreatestElement = getNextGreaterElementsFor(nums2);
+        int[] result = new int[nums1.length];
+        for (int index = 0 ; index < nums1.length ; index++) {
+            result[index] = nextGreatestElement.get(nums1[index]);
+        }
+        return result;
+    }
+
+    private static Map<Integer, Integer> getNextGreaterElementsFor(int[] array) {
+        Map<Integer, Integer> result = new HashMap<>();
+        Stack<Integer> stack = new Stack<>();
+
+        for (int element : array) {
+            while (!stack.isEmpty() && element > stack.peek()) {
+                result.put(stack.peek(), element);
+                stack.pop();
+            }
+            stack.push(element);
+        }
+
+        while (!stack.isEmpty()) {
+            result.put(stack.pop(), -1);
+        }
+
+        return result;
+    }
+
+    public static void main(String[] args) {
+        int[] result = nextGreaterElement(new int[] {4, 1, 2}, new int[] {1, 3, 4, 2});
+        System.out.println(Arrays.toString(result));
+    }
+}