A flowchart is a diagrammatic notation for representing algorithms. They show the control flow of algorithms using diagrams in a visual manner. In flowcharts, rectangular boxes represent simple statements, diamond-shaped boxes represent conditions, and arrows describe how the control flows during the execution of the algorithm. A flowchart is a collection of boxes containing statements and conditions which are connected by arrows showing the order in which the boxes are to be executed.

Symbol	Name	Uses/Represents
	Rectangle	Statements
	Diamond	Condition
	Parallelogram	Inputs, Outputs
	Oral/special boxes	start, end
\(\rightarrow \quad\leftarrow\quad \downarrow\quad\uparrow \)	Arrows	The direction of control flow
	Circle	Connector

1. A statement is contained in a rectangular box with a single outgoing arrow, which points to the box to be executed next.
2. A condition is contained in a diamond-shaped box with two outgoing arrows, labeled true and false. The true arrow points to the box to be executed next if the condition is true, and the false arrow points to the box to be executed next if the condition is false.
3. Parallelogram boxes represent inputs given and outputs produced.
4. Special boxes marked Start and the End is used to indicate the start and the end of execution:
The flowchart of an algorithm to compute the quotient and remainder after dividing an integer A by another integer B is shown below, illustrating the different boxes such as input, output, condition, and assignment, and the control flow between the boxes.
Flowcharts also have disadvantages.
(i) Flowcharts are less compact than the representation of algorithms in a programming language or pseudo code.
(ii) They obscure the basic hierarchical structure of the algorithms.
(iii) Alternative statements and loops are disciplined control flow structures. Flowcharts do not restrict us to disciplined control now structures.

The alternative statement analyses the problem into two cases. The case analysis statement generalizes it to multiple cases. Case analysis splits the problem into an exhaustive set of disjoint cases. For each case, the problem is solved independently. if Cl, C2, and C3 are conditions, and S1, S2, S3, and S4 are statements, a 4-case analysis statement has the form,
1. Case C1
2. S1
3. Case C2
4. S2
5. Case C3
6. S3
7. else
8.S4
The conditions C1, C2, and C3 are evaluated in turn. For the first condition that evaluates to true, the corresponding statement is executed, and the case analysis statement ends. If none of the conditions evaluates to true, then the default case S4 is executed.
1. The cases are exhaustive: at least one' of the cases is true. If all conditions are false, the default case is true.
2. The cases are disjoint: only one of the cases is true. Though it is possible for more than one condition to be true, the case analysis always executes only one case, the first one that is true. If the three conditions are disjoint, then the four cases are (1) C1, (2) C2, (3) C3, (4), (not C1) and (not C2) and (not C3).

Disadvantages of flowcharts:
1. Flowcharts are less compact than representation of algorithms in programming language or pseudo code.
2. They obscure the basic hierarchical structure of the algorithms.
3: Alternative statements and loops are disciplined control flow structures.

divide (A, B)
-- inputs: A is an integer and \(B\ne 0\)
 --outputs: q and r such that A = q X B + r and
--0 < r < B
q:= 0,A
while r > B
q, r:= q + 1, r - B