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| 1 | +/** |
| 2 | + * Title: Cheapest Flights Within K Stops |
| 3 | + * Description: There are n cities connected by some number of flights. You are given an array flights where flights[i] = [fromi, toi, pricei] indicates that there is a flight from city fromi to city toi with cost pricei. |
| 4 | + * Author: Hasibul Islam |
| 5 | + * Date: 04/05/2023 |
| 6 | + */ |
| 7 | + |
| 8 | +/** |
| 9 | + * @param {number} n |
| 10 | + * @param {number[][]} flights |
| 11 | + * @param {number} src |
| 12 | + * @param {number} dst |
| 13 | + * @param {number} k |
| 14 | + * @return {number} |
| 15 | + */ |
| 16 | +var findCheapestPrice = function (n, flights, src, dst, k) { |
| 17 | + let dMap = new Map(); |
| 18 | + |
| 19 | + for (let x = 0; x < flights.length; x++) { |
| 20 | + const [from, to, price] = flights[x]; |
| 21 | + if (dMap.has(from)) { |
| 22 | + let theArray = dMap.get(from); |
| 23 | + theArray[to] = price; |
| 24 | + dMap.set(from, theArray); |
| 25 | + } else { |
| 26 | + let theArray = new Array(n).fill(-1); |
| 27 | + theArray[from] = 0; |
| 28 | + theArray[to] = price; |
| 29 | + dMap.set(from, theArray); |
| 30 | + } |
| 31 | + } |
| 32 | + // Map structure = < nodeIndex, [cost price to directly connect to other node] |
| 33 | + |
| 34 | + //return -1 if there's src node has to edge to other node |
| 35 | + if (!dMap.has(src)) return -1; |
| 36 | + |
| 37 | + //BFS on src path |
| 38 | + let theQ = [[dMap.get(src), 0]]; |
| 39 | + let numOfStop = 0; |
| 40 | + const dist = new Array(n).fill(Infinity); |
| 41 | + let temp = []; |
| 42 | + while (numOfStop <= k && theQ.length > 0) { |
| 43 | + temp = []; |
| 44 | + for (let y = 0; y < theQ.length; y++) { |
| 45 | + const [city, cost] = theQ[y]; |
| 46 | + |
| 47 | + for (let x = 0; x < city.length; x++) { |
| 48 | + if (city[x] !== 0 && city[x] !== -1) { |
| 49 | + if (city[x] + cost >= dist[x]) continue; |
| 50 | + |
| 51 | + dist[x] = cost + city[x]; |
| 52 | + if (dMap.has(x)) { |
| 53 | + temp.push([dMap.get(x), cost + city[x]]); |
| 54 | + } |
| 55 | + } |
| 56 | + } |
| 57 | + } |
| 58 | + |
| 59 | + numOfStop++; |
| 60 | + theQ = temp; |
| 61 | + } |
| 62 | + return dist[dst] !== Infinity ? dist[dst] : -1; |
| 63 | +}; |
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