Merge branch 'main' into main

Author: ScorchedPearl

algos/range_queries/PrefixSum/soln/HimanshuArora-pixel/solution_1.py

@@ -0,0 +1,38 @@
+
+"""
+PROBLEM:
+We need to find the sum of numbers from(st to ed) in a list.
+
+Approach:
+We create a list which stores the sum of numbers from list till that index
+
+To find the sum from index st to ed':
+   Take total till ed and subtract total till st - 1.
+
+Time complexity:
+ Initial processing: O(n)
+ Finding Sum of the range: O(1)
+"""
+
+
+class Processor:
+    def __init__(self, nums):
+        self.prefix = []
+        total_till_now = 0
+
+        for n in nums:
+            total_till_now += n
+            self.prefix.append(total_till_now)
+
+
+    def sum_of_range(self, st, ed):
+
+        if st == 0:
+            return self.prefix[ed]
+
+        return self.prefix[ed] - self.prefix[st-1] #st-1 cause in sum range st is also included
+
+#Example:
+# nums = [1, 2, 3, 4, 5]
+# trial = Processor(nums)
+# print(trial.sum_of_range(2, 4)) # Sum of [3, 4, 5] = 12

contributers.md

@@ -16,6 +16,8 @@
 | Rushal Verma            | Rushalverma          | IIIT allahabad                 |
 | Avaneesh Verma          | avaneeshk2307-wq     | IIIT Allahabad                 |
 | Aditi Guin              | GuinAditi            | KIIT                            |
-
+| Saurav Gitte            | SauravGitte          | IIIT Allahabad                 |
+| Sourish Awasthi         | LooninS              | IIIT Allahabad                 |
+| Saumya Sood             | Marcella2706         | IIIT Allahabad                 |
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 <!-- example | Korvac | Betty41 | Reyansh College | -->