为什么计算的值错误

我有一个程序，可以计算不同日期和时间不同费率的电话费用。费率如下：

• 周一至周五上午 8：00 至下午 6：00 之间的任何呼叫均按每分钟 0.40 美元的费率计费。

• 周一至周五上午 8：00 之前或下午 6：00 之后拨打的任何电话均按每分钟 0.25 美元收费。

• 周六或周日拨打的任何电话均按每分钟 0.15 美元的费率收费。

• 持续时间跨越多个费率区的任何呼叫都将根据相应费率区中的实际分钟数收费。

我的代码为每个日志提供了正确的值，除了最后一个日志，它应该是 6.50 美元，但实际上是 4.50 美元。

代码如下：

#include <iostream>
#include <string>
#include <fstream>
#include <sstream>
#include <algorithm>
#include <iterator>
using namespace std;
string makeTimeIntoInt(string line[]) {
    string temp = "";
    string time = line[1];
    for (char a : time) {
        if (a == ':')
            continue;
        else
            temp += a;
    }
    return temp;
}
string nextDay(string day){
    if(day == "Mo") return "Tu";
    else if(day == "Tu") return "We";
    else if(day == "We") return "Th";
    else if(day == "Th") return "Fr";
    else if(day == "Fr") return "Sa";
    else if(day == "Sa") return "Su";
    else if(day == "Su") return "Mo";
    return day;
}
int convertSixtySecondsToHour(int time){
    if(time == 060) time = 100;
    else if(time == 160) time = 200;
    else if(time == 260) time = 300;
    else if(time == 360) time = 400;
    else if(time == 460) time = 500;
    else if(time == 560) time = 600;
    else if(time == 660) time = 700;
    else if(time == 760) time = 800;
    else if(time == 860) time = 900;
    else if(time == 960) time = 1000;
    else if(time == 1060) time = 1100;
    else if(time == 1160) time = 1200;
    else if(time == 1260) time = 1300;
    else if(time == 1360) time = 1400;
    else if(time == 1460) time = 1500;
    else if(time == 1560) time = 1600;
    else if(time == 1660) time = 1700;
    else if(time == 1760) time = 1800;
    else if(time == 1860) time = 1900;
    else if(time == 1960) time = 2000;
    else if(time == 2060) time = 2100;
    else if(time == 2160) time = 2200;
    else if(time == 2260) time = 2300;
    else if(time == 2360) time = 000;
    return time;
}
float calculateCost(string line[]) {
    int time = stoi(makeTimeIntoInt(line));
    int duration = stoi(line[2]);
    string day = line[0];
    float totalCost = 0;
    for(int i = 1; i <= duration; i++){
    if (line[0] == "Mo" || line[0] == "Tu" || line[0] == "We" ||
        line[0] == "Th" || line[0] == "Fr") {
        if (time < 800 || time > 1800) {
            totalCost += 0.25;
        } else
            totalCost += 0.4;
    }
    else if (line[0] == "Sa" || line[0] == "Su") {
        totalCost += 0.15;
    }
        time++;
        time = convertSixtySecondsToHour(time);
            if(time == 000){
            day = nextDay(day);
        }
    }
    return totalCost;
}
int main() {
    ifstream inputFile;
    string line;
    int cnt = 0;
    inputFile.open("/Users/wonder-intern/Documents/C++ Workspace/PhoneRecords/PhoneRecords/calls_history.txt"); //change this to the path of the txt file
    string arr[18];
    string line1[3], line2[3], line3[3], line4[3], line5[3], line6[3];
    float costLine1, costLine2, costLine3, costLine4, costLine5, costLine6;
    if (!inputFile.is_open()) {
        cout << "file could not be openednn";
        return 0;
    }
    while (getline(inputFile, line) && cnt < 18) {
        istringstream split(line);
        split >> arr[cnt];
        cnt++;
        split >> arr[cnt];
        cnt++;
        split >> arr[cnt];
        cnt++;
    }
    inputFile.close();
    line1[0] = arr[0];
    line1[1] = arr[1];
    line1[2] = arr[2];
    line2[0] = arr[3];
    line2[1] = arr[4];
    line2[2] = arr[5];
    line3[0] = arr[6];
    line3[1] = arr[7];
    line3[2] = arr[8];
    line4[0] = arr[9];
    line4[1] = arr[10];
    line4[2] = arr[11];
    line5[0] = arr[12];
    line5[1] = arr[13];
    line5[2] = arr[14];
    line6[0] = arr[15];
    line6[1] = arr[16];
    line6[2] = arr[17];
    costLine1 = calculateCost(line1);
    costLine2 = calculateCost(line2);
    costLine3 = calculateCost(line3);
    costLine4 = calculateCost(line4);
    costLine5 = calculateCost(line5);
    costLine6 = calculateCost(line6);
    cout << "Day Time Duration Costnn";
    cout << line1[0] << " " << line1[1] << " " << line1[2] << " $" << costLine1
    << "n";
    cout << line2[0] << " " << line2[1] << " " << line2[2] << " $" << costLine2
    << "n";
    cout << line3[0] << " " << line3[1] << " " << line3[2] << " $" << costLine3
    << "n";
    cout << line4[0] << " " << line4[1] << " " << line4[2] << " $" << costLine4
    << "n";
    cout << line5[0] << " " << line5[1] << " " << line5[2] << " $" << costLine5
    << "n";
    cout << line6[0] << " " << line6[1] << " " << line6[2] << " $" << costLine6
    << "n";
    cout << "Total: $"
    << costLine1 + costLine2 + costLine3 + costLine4 + costLine5 + costLine6
    << "nn";
    return 0;
}

带有通话记录的文本文件可以在这里找到：https://drive.google.com/open?id=0Bysk6_x4B46uQko4dEpMNXZtY2M