Cheap flights within k stops

index.js

var findCheapestPrice = function(n, flights, src, dst, K) {
  let ins = new Array(n).fill(0).map(r => [])
  for (const [from, to, cost] of flights) {
    ins[to].push([from, cost])
  }
  let dp = new Array(K+2).fill(0).map(r => new Array(n).fill(Number.MAX_SAFE_INTEGER))
  for (let i = 0; i <= (K+1); i++) {
    for (let j = 0; j < n; j++) {
      if (j === src) {
        dp[i][j] = 0
      } else {
        if (i === 0) {
          continue
        }
        for (const [stop, cost] of ins[j]) {
          dp[i][j] = Math.min(dp[i][j], cost + dp[i-1][stop])
        }
      }
    }
  }
  return dp[K+1][dst] === Number.MAX_SAFE_INTEGER ? -1 : dp[K+1][dst]
};