giles
fed07059a3
Some checks failed
Test, Build, and Deploy / test-build-deploy (push) Failing after 23s
Classic O(n) greedy gas-station algorithm:
walk once, tracking
total = sum of (gas[i] - cost[i]) -- if negative, no answer
curr = running tank since start -- on negative, advance
start past i+1 and reset
if total < 0 then -1 else start
For gas = [1;2;3;4;5], cost = [3;4;5;1;2], unique start = 3.
Tests `total` + `curr` parallel accumulators, reset-on-failure
pattern.
202 baseline programs total.
22 lines
451 B
OCaml
22 lines
451 B
OCaml
let gas_circuit gas cost =
|
|
let n = Array.length gas in
|
|
let total = ref 0 in
|
|
let curr = ref 0 in
|
|
let start = ref 0 in
|
|
for i = 0 to n - 1 do
|
|
let diff = gas.(i) - cost.(i) in
|
|
total := !total + diff;
|
|
curr := !curr + diff;
|
|
if !curr < 0 then begin
|
|
start := i + 1;
|
|
curr := 0
|
|
end
|
|
done;
|
|
if !total < 0 then -1 else !start
|
|
|
|
;;
|
|
|
|
let gas = [| 1; 2; 3; 4; 5 |] in
|
|
let cost = [| 3; 4; 5; 1; 2 |] in
|
|
gas_circuit gas cost
|