You are given an array of positive integers nums.Return the number of subarrays of nums, where the first and the last elements of the subarray are equal to the largest element in the subarray. Example 1:Input: nums = [1,4,3,3,2]Output: 6Explanation:There are 6 subarrays which have the first and the last elements equal to the largest element of the subarray:subarray [1,4,3,3,2], with its largest element 1. The first element is 1 and the last element is also 1.subarray [1,4,3,3,2], with its largest element 4. The first element is 4 and the last element is also 4.subarray [1,4,3,3,2], with its largest element 3. The first element is 3 and the last element is also 3.subarray [1,4,3,3,2], with its largest element 3. The first element is 3 and the last element is also 3.subarray [1,4,3,3,2], with its largest element 2. The first element is 2 and the last element is also 2.subarray [1,4,3,3,2], with its largest element 3. The first element is 3 and the last element is also 3.Hence, we return 6.Example 2:Input: nums = [3,3,3]Output: 6Explanation:There are 6 subarrays which have the first and the last elements equal to the largest element of the subarray:subarray [3,3,3], with its largest element 3. The first element is 3 and the last element is also 3.subarray [3,3,3], with its largest element 3. The first element is 3 and the last element is also 3.subarray [3,3,3], with its largest element 3. The first element is 3 and the last element is also 3.subarray [3,3,3], with its largest element 3. The first element is 3 and the last element is also 3.subarray [3,3,3], with its largest element 3. The first element is 3 and the last element is also 3.subarray [3,3,3], with its largest element 3. The first element is 3 and the last element is also 3.Hence, we return 6.Example 3:Input: nums = [1]Output: 1Explanation:There is a single subarray of nums which is [1], with its largest element 1. The first element is 1 and the last element is also 1.Hence, we return 1. Constraints:1 <= nums.length <= 1051 <= nums[i] <= 109
Question
You are given an array of positive integers nums.Return the number of subarrays of nums, where the first and the last elements of the subarray are equal to the largest element in the subarray. Example 1:Input: nums = [1,4,3,3,2]Output: 6Explanation:There are 6 subarrays which have the first and the last elements equal to the largest element of the subarray:subarray [1,4,3,3,2], with its largest element 1. The first element is 1 and the last element is also 1.subarray [1,4,3,3,2], with its largest element 4. The first element is 4 and the last element is also 4.subarray [1,4,3,3,2], with its largest element 3. The first element is 3 and the last element is also 3.subarray [1,4,3,3,2], with its largest element 3. The first element is 3 and the last element is also 3.subarray [1,4,3,3,2], with its largest element 2. The first element is 2 and the last element is also 2.subarray [1,4,3,3,2], with its largest element 3. The first element is 3 and the last element is also 3.Hence, we return 6.Example 2:Input: nums = [3,3,3]Output: 6Explanation:There are 6 subarrays which have the first and the last elements equal to the largest element of the subarray:subarray [3,3,3], with its largest element 3. The first element is 3 and the last element is also 3.subarray [3,3,3], with its largest element 3. The first element is 3 and the last element is also 3.subarray [3,3,3], with its largest element 3. The first element is 3 and the last element is also 3.subarray [3,3,3], with its largest element 3. The first element is 3 and the last element is also 3.subarray [3,3,3], with its largest element 3. The first element is 3 and the last element is also 3.subarray [3,3,3], with its largest element 3. The first element is 3 and the last element is also 3.Hence, we return 6.Example 3:Input: nums = [1]Output: 1Explanation:There is a single subarray of nums which is [1], with its largest element 1. The first element is 1 and the last element is also 1.Hence, we return 1. Constraints:1 <= nums.length <= 1051 <= nums[i] <= 109
Solution
The problem is asking to return the number of subarrays where the first and the last elements of the subarray are equal to the largest element in the subarray.
Here is a Python solution using a dictionary to keep track of the indices of each number in the array:
def numSubarrays(nums):
count = 0
indices = {}
for i, num in enumerate(nums):
if num not in indices:
indices[num] = [i]
else:
indices[num].append(i)
for num in indices:
for i in range(len(indices[num])):
for j in range(i, len(indices[num])):
count += 1
return count
This function works by iterating over the array and storing the indices of each number in a dictionary. Then, for each number in the dictionary, it iterates over the indices and counts the number of subarrays where the first and last elements are equal to the current number.
For example, given the input [1,4,3,3,2], the function will return 6, as there are 6 subarrays where the first and last elements are equal to the largest element in the subarray.
Similar Questions
Given an integer array nums, find the subarray with the largest sum, and return its sum.
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