06-diwali-lights.js

1/**
2 * 🪔 Sharma ji ki Diwali Decoration
3 *
4 * Sharma ji apne ghar ko Diwali pe sajana chahte hain light strings se.
5 * Unke paas ek budget hai aur market mein alag alag colors ki light strings
6 * hain different lengths mein. Sharma ji sab kuch lena chahte hain, lekin
7 * budget se zyada nahi!
8 *
9 * Color rates (per meter):
10 *   - "golden" = Rs 50/meter
11 *   - "multicolor" = Rs 40/meter
12 *   - "white" = Rs 30/meter
13 *   - Any other color = Rs 35/meter
14 *
15 * Rules:
16 *   Step 1 - Use for...of to loop through lightStrings and add ALL of them
17 *     to selected list with their cost calculated
18 *   Step 2 - Use a while loop to check: agar totalCost > budget, toh remove
19 *     the LAST item from selected, subtract its cost, and keep removing until
20 *     totalCost <= budget
21 *
22 * @param {Array<{color: string, length: number}>} lightStrings - Available light strings
23 * @param {number} budget - Sharma ji ka budget in rupees
24 * @returns {{ selected: Array<{color: string, length: number, cost: number}>, totalLength: number, totalCost: number }}
25 *
26 * Validation:
27 *   - Agar lightStrings array nahi hai ya budget positive number nahi hai,
28 *     return: { selected: [], totalLength: 0, totalCost: 0 }
29 *
30 * @example
31 *   diwaliLightsPlan(
32 *     [{ color: "golden", length: 5 }, { color: "white", length: 10 }, { color: "multicolor", length: 3 }],
33 *     400
34 *   )
35 * 
36 *    golden: 5*50=250, white: 10*30=300, multicolor: 3*40=120
37 *   Total = 670 > 400, remove multicolor (670-120=550), still > 400,
38 *    remove white (550-300=250), 250 <= 400
39 *    => { selected: [{ color: "golden", length: 5, cost: 250 }], totalLength: 5, totalCost: 250 }
40 */
41export function diwaliLightsPlan(lightStrings, budget) {
42  if(!Array.isArray(lightStrings) || budget < 0 || typeof budget !== "number"){
43    return  {selected: [], totalLength: 0, totalCost: 0 }
44  }
45
46  let selected = [];
47  let totalCost = 0;
48  let totalLength = 0;
49
50  function getRateByColor(color){
51     switch(color) {
52        case "golden": return 50;
53        case "multicolor": return 40;
54        case "white": return 30;
55        default: return 35;
56    }
57  }
58
59  for(const item of lightStrings){
60    const rate = getRateByColor(item.color)
61
62    const cost = rate*item.length
63    
64    selected.push({
65      color:item.color,
66      length: item.length,
67      cost
68    })
69
70    totalCost += cost
71    totalLength += item.length
72  }
73
74  while(totalCost > budget && selected.length > 0){
75    const removedItem = selected.pop()
76    totalCost -= removedItem.cost;
77    totalLength -= removedItem.length
78  }
79  return {
80    selected, totalLength, totalCost
81  }
82}
83