Counting Steps

  • Count RAM instructions for a given code snippet.

Exercise Under the RAM model, what is the total number of steps it will take to execute the following code snippet? 

int count = 0;  
for (int i = 0; i < 10; i++) {  
    for (int j = 0; j < 5; j++) {  
        count++;  
    }   
}  
System.out.println(count);

A) about $50$
B) about $200$
C) about $1000$

Solution

Answer: about 200.

int count = 0;                     // 1
for (int i = 0; i < 10; i++) {     // 1 + 11 + 10
    for (int j = 0; j < 5; j++) {  // (1 + 6 + 5) * 10
        count++;                   // (1 * 5) * 10
    }   				  
}  					   
System.out.println(count);         // 1

Note we ask for approximate because the details can get tricky (e.g. i < 10 runs 11 times where ten times i is less than 10 and one last time it is equal to 10).