The Ascending Iterator

LINQ never ceases to amaze me. Recently, while working on a problem in the Google CodeJam, I realised that using LINQ can reduce code and make your code look clean, compact and elegant. So here’s showcasing the LINQ extension method that made my day – Aggregate. Here are three interesting uses of the Aggregate method that I could think of which makes writing the usual for loops so C# 2.0 (or 2006, whichever you prefer).

The first example is what I actually used to solve one of the CodeJam problems. The second example is one of my interview screener questions, reversing the words in a sentence. The third example materialized when I realized that the process of converting a binary number to base 10 fits very well in the aggregation logic.

// Aggregate works on any IEnumerable<T> collection
IEnumerable<int> collection = new int[5] {1, 2, 3, 4, 5}; 

// Example 1: XOR all the integers in the collection. 
int xorResult = 
  collection.Aggregate(
    (runningResult, next) => runningResult ^ next);

// Example 2: Reverse words in a sentence
string[] words = "that's what she said".Split(' ');
// Observe the way we are concatenating the strings
string reversed = 
  words.Aggregate(
    (sentence, next) => next + " " + sentence);

// Example 3: Convert base 2 int to base 10 int
int[] base2 = new int[] { 1, 1, 1, 0, 0 };
int base10 = 
  base2.Aggregate(0, (result, next) => 2 * result + next);