[백준] 11501번 주식

흠...

 

import sys
for i in range(int(input())):
    stockLen = int(input())
    stockData = list(map(int, sys.stdin.readline().split()))
    stockData.insert(0, 1000001)
    tempStock = [stockData[-1]]
    tempVal  = stockData[-1]
    ans = 0
    for i in range(stockLen - 1, -1, -1):
        if stockData[i] < tempVal:
            tempStock.append(stockData[i])
        else:
            for j in tempStock:
                ans += tempVal - j
            tempVal = stockData[i]
            tempStock = [tempVal]
    print(ans)