CSE 2341 Honors Professor Mark Fontenot Southern Methodist University Note Set 03

Overview Search a 1D array Sort a 1D array 2D arrays

Linear Search Goal: Find the location of a particular element in an array Process: Start at the beginning, compare each element in the array to the value being searched for Remember: Array’s aren’t self aware of their size.

Source Code int linSearch(const int arr[], int key, int arrSize) { for (int j = 0; j < arrSize; j++) if(arr[j] == key) return j; return -1; }

Binary Search Input: Sorted Array Goal: Find the location of an element in an array if it exists Process: Compare key with middle element in the array. – If key < middle, element must be in lower half of array – if key > middle, element must be in upper half of array – else key found

Sorting Classic problem in CS and very well studied Probably hundreds of sorting algorithms out there. Typically, sorted data is “easier” to work with than unsorted data Insertion Sort: – Process: Take 2 nd element and swap with 1 st if it is smaller. Take 3 rd element, insert into proper position with respect to 1 st and 2 nd. and so on…

2D Arrays 20 x 20 grid of integers access each element using 2 subscripts – cout << data[1][2]; – cin >> data[2][10]; Don’t make the mistake of – cout << data[1, 2]; int data[20][20];

2D array as matrix Write a program to read 2 matrices (of compatible size) out of a file and add them together.

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