Greatest of Brothers

Problem

Determine the maximum of a bunch of numbers.

19. Greatest of brothers, Comet 64

Solution 1

Read in the first value because all the integers might be negative. Cannot assume that all numbers are positive, hence cannot use the initial value of int as zero. Compare the running maximum to the current input. If the running maximum is less than the current input, then we have found a new running maximum. Otherwise read the next input.

int = input;               // The current maximum.
loop:                      // Start of loop.
    check input = null;    // No more numbers?
    jump if true: print;   // If so, go to "print".
    reg = input;           // Read the next number
    check int < reg;       // Is current max < input?
    jump if true: newMax;  // If so, go to "newMax".
    jump to: loop;         // Otherwise, go to "loop".
print:                     // The "print" branch.
    output = int;          // Print the running maximum.
newMax:                    // The "newMax" branch.
    int = reg;             // The new maximum value.
    jump to: loop;         // Go to "loop".

Solution 2

Similar to Solution 1, but we remove a jump instruction.

int = input;              // The running maximum.
loop:                     // Start of "loop".
    check input = null;   // No more numbers?
    jump if true: print;  // If so, go to "print".
    reg = input;          // Read the next number.
    check int < reg;      // Is current max < input?
    jump if false: loop;  // If not, go to "loop".
    int = reg;            // The new maximum value.
    jump to: loop;        // Go to "loop".
print:                    // The "print" branch.
    output = int;         // Print the running maximum.

Solution 3

Similar to Solution 2, but we remove a jump instruction. Only peek at the next input value after we have updated the current maximum. This solution is optimal, according to the game.

int = input;              // Current maximum.
loop:                     // Start of "loop".
    reg = input;          // Read the next number.
    check int < reg;      // Is current max < input?
    jump if false: peek;  // If not, go to "peek".
    int = reg;            // Otherwise, update the maximum.
peek:                     // The "peek" branch.
    check input = null;   // No more numbers?
    jump if false: loop;  // If still more, go to "loop".
output = int;             // Print the running maximum.