https://www.pramp.com/challenge/2WBx3Axln1t7JQ2jQq96

findBusiestPeriod.swift

// Problem: https://www.pramp.com/challenge/2WBx3Axln1t7JQ2jQq96

func findBusiestPeriod(data: [[Int]]) -> Int {
    var timeStamp = 0
    
    var busiest = -1
    var currentBusiest = 0
    
    let length = data.count
    
    for (index, eachArray) in data.enumerated() {
      
        let state = eachArray[2]
        let visitors = eachArray[1]
        let currentTimeStamp = eachArray[0]
        
        if state == 1 {
            currentBusiest += visitors
        } else {
            currentBusiest -= visitors
        }
        
        if (index < length - 1) && currentTimeStamp == data[index + 1][0] {
            continue
        } 
      
        if currentBusiest > busiest {
            busiest = currentBusiest
            timeStamp = currentTimeStamp
        }
    }
    
    return timeStamp
}

/*
input:  data = [ [1487799425, 14, 1], 
                 [1487799425, 4,  0],
                 [1487799425, 2,  0],
                 [1487800378, 10, 1],
                 [1487801478, 18, 0],
                 [1487801478, 18, 1],
                 [1487901013, 1,  0],
                 [1487901211, 7,  1],
                 [1487901211, 7,  0] ]

output: 1487800378 # since the increase in the number of people
                   # in the mall is the highest at that point
*/