6.3.2. Problema de las n reinas.
NReinasBacktracking (var s: array [1.. n] of integer)
while (s[nivel] ? n) and not Criterio (nivel, s) do
if (nivel=n) and (s[nivel] ? n) then
else if (s[nivel] ? n) then
Criterio (nivel: 0..n; s: array [1.. n] of integer) : boolean
if (s[nivel]=s[i]) or |s[i] - s[nivel]| = |i - nivel| then