Hacker Rank: Stock Maximize

//
//  main.m
//  Stock Maximize
//
//  Created by Nathan Arnold on 11/1/15.
//  Copyright © 2015 Nathan Arnold. All rights reserved.
//

#import <Foundation/Foundation.h>


/*
 def calcprofit(stockvalues):
 dobuy=[1]*len(stockvalues) # 1 for buy, 0 for sell
 prof=0
 m=0
 for i in range(len(stockvalues)-1,-1,-1): # reverse loop
 ai=stockvalues[i] # shorthand name
 if m<=ai:
 dobuy[i]=0
 m=ai
 prof+=m-ai
 return (prof,dobuy)
 */


long calculateProfit(int stockValues[], int length){
    
    BOOL shouldBuy[length];
    long money = 0;
    long prof = 0;
    //Go reverse order
    for (int i = length-1; i >= 0; i--) {
        int val = stockValues[i];
        if (money <= val) {
            shouldBuy[i] = NO;
            money = val;
        }
        
        prof+=money-val;
    }

    return prof;
}


void processTestCase() {
    
    int numberOfPrices = 0;
    scanf("%d", &numberOfPrices);
    
    int prices[numberOfPrices];
    
    for (int i = 0; i < numberOfPrices; i++){
        scanf("%d",&prices[i]);
    }
    
    printf("%ld\n",calculateProfit(prices, numberOfPrices));
}


int main(int argc, const char * argv[]) {
    @autoreleasepool {
        // insert code here...
        
        int numberOfTestCases = 0;
        scanf("%d", &numberOfTestCases);
        
        for (int i = 0; i < numberOfTestCases; i++){
            processTestCase();
        }
    }
    
    return 0;
}