Sales Target Ranges

Medium

Sales Target Ranges

Find the number of contiguous subarrays with sum equal to K

📊 Complexity

Type	Value
Best	O(n)
Average	O(n)
Worst	O(n)
Space	O(n)

🏷️ Tags

Prefix SumHashMapSubarray

📋 Problem

Sales Target Ranges

You are analyzing daily sales data for a store. Find how many contiguous periods have a total sales sum exactly equal to the target amount K. Negative values represent refunds or losses.

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🎯Array with Negatives!

Find all contiguous subarrays with sum K=5 in [2, 3, -1, 1, 5]! -1 means sliding window won't work!

Sales Target Ranges

Description

You are analyzing daily sales data for a store. Find how many contiguous periods have a total sales sum exactly equal to the target amount K. Negative values represent refunds or losses.

Input

Array of daily sales and target amount K

Output

Number of contiguous subarrays with sum K

Constraints

•1 <= array length <= 20,000
•-1,000 <= each element <= 1,000
•-10,000,000 <= K <= 10,000,000

Examples

Example 1

Input

sales = [1, 2, 3, -2, 5], K = 5

Output

Explanation

Subarrays with sum 5: • [2, 3] → 2+3=5 ✓ • [5] → 5 ✓ • Index 1~2: 2+3=5 ✓ • Index 4: 5 ✓ Total: 2 (Corrected example) sales = [1, 1, 1], K = 2 • [1,1] (index 0~1) ✓ • [1,1] (index 1~2) ✓ Total: 2!

Example 2

Input

sales = [2, 3, -1, 1, 5], K = 5

Output

Explanation

Subarrays with sum 5: • [2, 3] = 5 ✓ • [2, 3, -1, 1] = 5 ✓ (includes negative!) • [-1, 1, 5] = 5 ✓ • [5] = 5 ✓ Total: 4!

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