TaskExecution.php

<?php
// This is the text editor interface.
// Anything you type or change here will be seen by the other person in real time. 

// You are given tasks which can be identified as A, B, ...
// Execution of eack task takes tA, tB, ... time
// If you execute task A, you have to wait dA time before executing task A again
// If you are given a sequence of tasks and asked to execute sequentially, how long would it take to execute them?
//
// A B C A A D B 
//
// tA = 5
// tB = 1
// tC = 1
// tD = 2
//
// dA = 5
// dB = 2
// dC = 2
// dD = 3
//
// 5(tA) + 1(tB) + 1(tC) + 3(dA:5 - 2) + 5(tA) + 5(dA) + 5(tA) + 2(tD) + 1(tB) = 28
//     A +  1    +   1   + waiting 3   + A  
//array signature for each task : taskname, executionTime, waitTime

$tasksInfo = array( 
    
        array('A', 5, 5), 
        array('B',1,2), 
        array('C', 1,2), 
        array('D', 2, 3)
);



$inputTaskSequence = array ('A', 'B','C', 'A', 'A', 'D', 'B');


// task#1: AA
// task#2: BB
// task#3: CCCCC
// .
// 1000s of distinct tasks

function array_search_custom ($task, $taskInfo) { //search multidimentional array for values
    
    foreach ($taskInfo as $key => $t) {
        
        if ($t[0] ===  $task) return $key;
    }
    
    return false;
}

function taskExecutionTime($input, $taskCount, $tasksInfo){
    
   

        $time = 0; 
        
        $taskStack = array ();
        
        // 5(tA) + 1(tB) + 1(tC) + 3(dA:5 - 2) + 5(tA) + 5(dA) + 5(tA) + 2(tD) + 1(tB) = 28
        //     A +  1    +   1   + waiting 3   + A  
        
        for($i = 0; $i < $taskCount; $i++) {
            
            
            $currentTask = $input[$i];
            echo "\nhere: ".$currentTask; 
             
             //// If you execute task A, you have to wait dA time before executing task A again
            
            if (!empty($taskStack) && in_array($currentTask, $taskStack)) {
                
                //this task was already started and is in taskStack, now need to wait before executing this again
                //need to calculate: time elapsed since the task
                //check if this is less than or equal to wait time
                // simply: waitTime for this task - time elapsed since this tasks was pushed to stack
                
                $elapsedTime =0;
                $waitTime = 0;
                 
                echo "\n---------reverse---------";
                
                for($elapsedIndex = $i -1 ; $elapsedIndex >= 0; $elapsedIndex--) {
                    
                    echo "\nrepeated task: " . $repeatedTask = $currentTask;
                    echo "\nprevious task: " . $previousTask = $taskStack[$elapsedIndex];
                    echo "\n";
                    
                    if ($repeatedTask != $previousTask) {
                        
                        $k = array_search_custom ($previousTask, $tasksInfo); //find info about previous task
                        print_r($tasksInfo[$k]);
                        $elapsedTime +=   $tasksInfo[$k][1]; //save its execution time to elapsed time
                        
                    }else {
                        
                        $elapsedTime +=   $tasksInfo[$k][2];
                        break;
                    }
                    
                }
                
                echo "\n---------reverse---------";
                
                // A B C A A D B 
                // 5(tA) + 1(tB) + 1(tC) + 3(dA:5 - 2) + 5(tA) + 5(dA) + 5(tA) + 2(tD) + 1(tB) = 28
                // 5 +  1    +   1   + waiting 3   + 5 + waiting 5 + 5 + 2 + 1 = 28  
                
                $k = array_search_custom ($currentTask, $tasksInfo);
                
                 echo "\nElapsed time: " . $elapsedTime . PHP_EOL;
            
            
                if ($tasksInfo[$k][2] > $elapsedTime) {
                    
                    $waitTime =  $tasksInfo[$k][2] - $elapsedTime;  //waitTime - timeElapsed  
                } else {
                    
                    $waitTime += $elapsedTime; //$tasksInfo[$k][1];
                } 
                
                $time += $waitTime;
                
            
                
            }else {
                
                //find task by Value
                
               
                
                $key = array_search_custom ($currentTask, $tasksInfo);
                
                echo "\nkey: " . $key . PHP_EOL;
                
                $time += $tasksInfo[$key][1];
                
                print_r($tasksInfo[$key]);
             
                echo "Execution time: " . $tasksInfo[$key][1] . PHP_EOL;
            }
            
            array_push($taskStack, $currentTask);
               
               
            //print_r($taskStack);
            
            echo "Total time " . $time;
            echo PHP_EOL;   
            
           
        }
        
        return $time; 

}

echo taskExecutionTime($inputTaskSequence, count($inputTaskSequence), $tasksInfo);

?>