Commonly used heuristics for this problem include counting the number of misplaced tiles and finding the sum of the Manhattan distances between each block and its position in the goal configuration.
Green function | Graph of a function | Hash function | Schur function | Riemann zeta function | Dirac delta function | Bessel function | Monotonic function | Lateralization of brain function | function (mathematics) | Cryptographic hash function | Linear function | heuristic | hash function | Gaussian function | function | Euler's totient function | Domain of unknown function | continuous function | Wave function | Quadratic function | Meijer G-function | Massieu function | Lyapunov function | Lambert W function | Gamma function | Function block diagram | Feigenbaum function | Continuous function | Computable function |