Add problem 496

Author: avhn

algorithms/496/README.md

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+## 496. Next Greater Element I
+
+You are given two arrays **(without duplicates)** `nums1` and `nums2` where `nums1`’s elements are subset of `nums2`. Find all the next greater numbers for `nums1`'s elements in the corresponding places of `nums2`.
+
+The Next Greater Number of a number **x** in `nums1` is the first greater number to its right in `nums2`. If it does not exist, output -1 for this number.
+
+**Example 1:**
+<pre>
+<b>Input:</b> <b>nums1</b> = [4,1,2], <b>nums2</b> = [1,3,4,2].
+<b>Output:</b> [-1,3,-1]
+<b>Explanation:</b>
+ For number 4 in the first array, you cannot find the next greater number for it in the second array, so output -1.
+ For number 1 in the first array, the next greater number for it in the second array is 3.
+ For number 2 in the first array, there is no next greater number for it in the second
+ array, so output -1.
+</pre>
+
+
+**Example 2:**
+<pre>
+<b>Input:</b> <b>nums1</b> = [2, 4] <b>nums2</b> = [1,2,3,4].
+<b>Output:</b> [3,-1]
+<b>Explanation:</b>
+ For number 2 in the first array, the next greater number for it in the second array is 3.
+ For number 4 in the first array, there is no next greater number for it in the second
+ array, so output -1.
+</pre>
+
+
+**Note:**
+
+ 1. All elements in `nums1` and `nums2` are unique.
+ 2. The length of both `nums1` and `nums2` would not exceed 1000.

algorithms/496/solution.go

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+package main
+
+// Time complexity, O(n*m) where n is the length of the superset
+// and m is the length of subset
+// Space complexity, O(m)
+func nextGreaterElement(nums1 []int, nums2 []int) []int {
+res := make([]int, len(nums1))
+for i := 0; i < len(nums1); i++ {
+for j := 0; ; j++ {
+if nums1[i] == nums2[j] {
+for j++; j < len(nums2) && nums2[j] < nums1[i]; j++ {
+}
+if j < len(nums2) {
+res[i] = nums2[j]
+} else {
+res[i] = -1
+}
+break
+}
+}
+}
+return res
+}