in 写代码(coding)

长距离打车如何省钱?

学JavaScript的时候写的一个用于在长距离打车时,计算多远抬一次表最省钱的抬表方案的小程序,参数可以根据需要随意修改。

X轴是距离,Y轴是费用,不同的颜色表示不同的抬表方案

大致的简单结论是20公里以上的时候,每15公里抬一次表,能省出10%左右吧。

taxi 下面代码存为taxi.html,然后打开即可在浏览器中看到结果。


<html>
<script type="text/javascript" src="http://www.walterzorn.com/scripts/wz_jsgraphics.js"></script>

<body>
<script type="text/javascript">
<!--
function getPrice(distance, night) {
 var unitPrice = 2.0,
 basicDistance = 3,
 basicPrice = 10,
 extDistance = 15,
 extPrice = 3.0;

 var price = 0.0;
 if ( distance == 0 ) return 0;
 if ( distance <= basicDistance ) return basicPrice;

 if ( distance <= extDistance ) {
 price = basicPrice + unitPrice * (distance - basicDistance);
 return price;
 }

 price += basicPrice + unitPrice*(extDistance-basicDistance) + extPrice*(distance-extDistance)
 return price;
}

function getPriceWithReset(distance, night, reset) {
 if ( reset == 0 ) {
 return getPrice(distance, night);
 } else {
 return getPrice(reset, night) * Math.floor(distance/reset) + getPrice(distance % reset, night);
 }
}

var coordXUnit = 8, coordYUnit = 3,
basicX = 100, basicY = 50,
coordMaxX = 101, coordMaxY = 251;

function drawString(str, x, y) {
 jg.drawString(str, basicX+x*coordXUnit, basicY+(coordMaxY-y)*coordYUnit);
}

function drawPoint(x, y) {
 drawLine(x, y, x, y);
}

function drawLine(x1, y1, x2, y2) {
 jg.drawLine(basicX + x1*coordXUnit, basicY + (coordMaxY-y1)*coordYUnit, basicX + x2*coordXUnit, basicY + (coordMaxY-y2)*coordYUnit);
}

function drawPolyline(ax, ay) {
 var axx = new Array(), ayy = new Array();

 for (var e in ax) {
 axx.push(basicX + (ax[e] * coordXUnit) );
 }

 for (var e in ay) {
 ayy.push(basicY + (coordMaxY - ay[e])*coordYUnit);
 }

 jg.drawPolyline(axx, ayy);
}

function drawCoordinate() {
 jg.setColor("#ee8800");
 drawLine(0, 0, coordMaxX, 0);
 drawLine(0, 0, 0, coordMaxY);

 drawString(0, -2, -2);
 for (var i = 1; i < coordMaxX; i++) {
 if (i%5==0) {
 // draw grid
 jg.setStroke(Stroke.DOTTED);
 drawLine(i, 0, i, coordMaxY);
 // draw mark
 jg.setStroke(0);
 drawLine(i, 0, i, -2);
 drawString(i, i-1, -3);
 } else {
 drawLine(i, 0, i, -1);
 }
 }

 for (var i = 1; i < coordMaxY ; i++) {
 if (i%5==0) {
 // draw grid
 jg.setStroke(Stroke.DOTTED);
 drawLine(0, i, coordMaxX, i);
 // draw mark
 jg.setStroke(0);
 drawLine(0, i, -2, i);
 drawString(i, -7, i+1);
 } else {
 drawLine(0, i, -1, i);
 }
 }
}

function drawPriceLine(night, reset) {
 var ax = new Array(), ay = new Array();

 for (var d=0; d<70; d++) {
 ax.push(d);
 ay.push(getPriceWithReset(d, 0, reset));
 }
 drawPolyline(ax, ay);
}

/////////////// main section ///////////////
var jg = new jsGraphics();
jg.setFont("verdana,geneva,sans-serif", "10px", Font.PLAIN);

drawCoordinate();
drawString("reset:", 0, -10);
jg.setColor("#000000");
drawPriceLine(0, 0);
drawString("0", 5, -10);
jg.setColor("#FF0000");
drawPriceLine(0, 10);
drawString("10", 10, -10);
jg.setColor("#00FF00");
drawPriceLine(0, 15);
drawString("15", 15, -10);
jg.setColor("#0000FF");
drawPriceLine(0, 20);
drawString("20", 20, -10);

///////////////// from wangjing to my home, 35KM /////////////////
jg.setColor("#880000");
var xp = new Array(), yp = new Array();
for ( var i=10; i<30; i++) {
 xp.push(i);
 yp.push(getPriceWithReset(35, 0, i));
}
drawPolyline(xp, yp);

drawString(getPriceWithReset(35, 0, 15), 0, -20);
jg.paint();
//-->
</script>
</body>
</html>

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