Mancala World
Inventor: Gyula Horvath, 2001
Variant of Kalah
Ranks: Circle
Sowing: Single laps
Region: Hungary, Finland

Ioiwari, a mancala game, was especially developped by the Hungarian Gyula Horvath as a programming task for the International Olympiad in Informatics 2001 (or: IOI 2001) in Tampere, Finland. The first player always has a winning strategy. The game also participated in the Olimpiadi Italiane di Informatica 2005.


The game is played on circular board with seven holes around the edge. In addition, each player owns a store called "bank".

Initially there are 20 beads randomly distributed in the holes so that each one contains at least two and at most four beads.


One Random Set-up

The two players move alternately.

At his turn a player takes the contents of a non-empty hole in his hand. Then he considers the holes that follow in a clockwise direction by performing these actions:

More than one bead in his hand: If the considered hole numbers five beads, then he places one of its beads into his store, otherwise he puts one bead from his hand into the bank.

One bead in his hand: If the considered hole contains at least one and at most four beads, then he moves all beads from the pit and the one in his hand into his bank, otherwise (the hole has no or five beads) he puts the bead in his hand into the opponent's bank.

It is not permitted to pass a move.

The game ends when no move can be made.

The player who captured most beads has won the game.


Horvath, G. 
Ioiwari Game: Task Description. In: Nummenmaa, J., Mäkinnen, E. & Aho., I. (Ed.). IOI'01 Competition. Department of Computer and Information Sciences, University of Tampere, Tampere (Finland) 2001, 32-37 & 87-94.

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By: Ralf Gering & Víktor Bautista i Roca
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