We present a modification of the Depth first search algorithm, suited for finding long induced paths. We use it to give simple proofs of the following results. We show that the induced size-Ramsey number of paths satisfies
$\hat{R}_{\mathrm{ind}}(P_n)\leq 5 \cdot 10^7n$
, thus giving an explicit constant in the linear bound, improving the previous bound with a large constant from a regularity lemma argument by Haxell, Kohayakawa and Łuczak. We also provide a bound for the k-colour version, showing that
$\hat{R}_{\mathrm{ind}}^k(P_n)=O(k^3\log^4k)n$
. Finally, we present a new short proof of the fact that the binomial random graph in the supercritical regime,
$G(n,\frac{1+\varepsilon}{n})$
, contains typically an induced path of length
$\Theta(\varepsilon^2) n$
.