一.题目
Description
Adapted from Wikipedia, the free encyclopedia
The humidex is a measurement used by Canadian meteorologists to reflect the combined effect of heat and humidity. It differs from the heat index used in the United States in using dew point rather than relative humidity.
When the temperature is 30°C (86°F) and the dew point is 15°C (59°F), the humidex is 34 (note that humidex is a dimensionless number, but that the number indicates an approximate temperature in C). If the temperature remains
30°C and the dew point rises to 25°C (77°F), the humidex rises to 42.3.
The humidex tends to be higher than the U.S. heat index at equal temperature and relative humidity.
The current formula for determining the humidex was developed by J.M. Masterton and F.A. Richardson of Canada's Atmospheric Environment Service in 1979.
According to the Meteorological Service of Canada, a humidex of at least 40 causes "great discomfort" and above 45 is "dangerous." When the humidex hits 54, heat stroke is imminent.
The record humidex in Canada occurred on June 20, 1953, when Windsor, Ontario hit 52.1. (The residents of Windsor would not have known this at the time, since the humidex had yet to be invented.) More recently, the humidex reached
50 on July 14, 1995 in both Windsor and Toronto.
The humidex formula is as follows:
humidex = temperature + h
h = (0.5555)× (e - 10.0)
e = 6.11 × exp [5417.7530 × ((1/273.16) - (1/(dewpoint+273.16)))]
where exp(x) is 2.718281828 raised to the exponent x.
While humidex is just a number, radio announcers often announce it as if it were the temperature, e.g. "It's 47 degrees out there ... [pause] .. with the humidex,". Sometimes weather reports give the temperature and dewpoint,
or the temperature and humidex, but rarely do they report all three measurements. Write a program that, given any two of the measurements, will calculate the third.
You may assume that for all inputs, the temperature, dewpoint, and humidex are all between -100°C and 100°C.
Input
Input will consist of a number of lines. Each line except the last will consist of four items separated by spaces: a letter, a number, a second letter, and a second number. Each letter specifies the meaning of the number that
follows it, and will be either T, indicating temperature, D, indicating dewpoint, or H, indicating humidex. The last line of input will consist of the single letter E.
Output
T number D number H number
where the three numbers are replaced with the temperature, dewpoint, and humidex. Each value should be expressed rounded to the nearest tenth of a degree, with exactly one digit after the decimal point. All temperatures are in degrees
celsius.
Sample Input
T 30 D 15
T 30.0 D 25.0
E
Sample Output
T 30.0 D 15.0 H 34.0
T 30.0 D 25.0 H 42.3
二.解题技巧
cout.precision(1); //设置输出精度为小数点后1位
三.实现代码
#include <iostream>
using namespace std;
#include <cmath>
#include <stdio.h>
double CalEFromD(double Dew)
{
double tmp = exp(5417.7530 * ((1.0 / 273.16) - (1.0 / (Dew + 273.16))));
tmp = 6.11 * tmp;
return tmp;
}
double CalEFrowH(double H)
{
double E = H / 0.5555 + 10;
return E;
}
double CalHFromE(double E)
{
double H = 0.5555 * (E - 10.0);
return H;
}
double CalHFromTemAndHum(double Tem, double Hum)
{
double H = Hum - Tem;
return H;
}
double CalHumFromTemandDew(double Tem, double Dew)
{
double E = CalEFromD(Dew);
double H = CalHFromE(E);
double Hum = Tem + H;
return Hum;
}
double CalTemFrowDewandHum(double Dew, double Hum)
{
double E = CalEFromD(Dew);
double H = CalHFromE(E);
double Tem = Hum - H;
return Tem;
}
double CalDewFrowTemandHum(double Tem, double Hum)
{
double H = Hum - Tem;
double E = CalEFrowH(H);
double tmp = E / 6.11;
tmp = log(tmp);
tmp = tmp / 5417.7530;
tmp = 1 / 273.16 - tmp;
tmp = 1 / tmp;
double Dew = tmp - 273.16;
return Dew;
}
void Output(double Tem, double Dew, double Hum)
{
cout << "T " << Tem << " D " << Dew << " H " << Hum << endl;
}
const int TEM = 1;
const int DEW = 2;
const int HUM = 4;
const int TEMDEW = TEM | DEW;
const int TEMHUM = TEM | HUM;
const int DEWHUM = DEW | HUM;
void Calc(double& Tem, double& Dew, double& Hum, int& Mode)
{
switch (Mode)
{
case TEMDEW:
Hum = CalHumFromTemandDew(Tem, Dew);
Output(Tem, Dew, Hum);
Mode = 0;
break;
case TEMHUM:
Dew = CalDewFrowTemandHum(Tem, Hum);
Output(Tem, Dew, Hum);
Mode = 0;
break;
case DEWHUM:
Tem = CalTemFrowDewandHum(Dew, Hum);
Output(Tem, Dew, Hum);
Mode = 0;
break;
default:
break;
}
}
int main()
{
bool IsWorks = true;
int Mode = 0;
double Tem = 0.0;
double Dew = 0.0;
double Hum = 0.0;
char Type = 'A';
cout << std::fixed ;
cout.precision(1);
while (IsWorks)
{
cin >> Type;
switch (Type)
{
case 'T':
cin >> Tem;
Mode = Mode | TEM;
Calc(Tem, Dew, Hum, Mode);
break;
case 'D':
cin >> Dew;
Mode = Mode | DEW;
Calc(Tem, Dew, Hum, Mode);
break;
case 'H':
cin >> Hum;
Mode = Mode | HUM;
Calc(Tem, Dew, Hum, Mode);
break;
case 'E':
IsWorks = false;
break;
default:
break;
}
}
return 0;
}
四.体会
