86 lines
2.2 KiB
Go
86 lines
2.2 KiB
Go
package opponent
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import (
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"math"
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"tictactoe/gamecontrol"
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)
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type NextMove struct {
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Row int
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Col int
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score int
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}
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// iterative implementation of minimax algorithm
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func Minimax(board [3][3]string, depth int, isMaximizingPlayer bool, player string) NextMove {
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// check if the game has ended
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if gamecontrol.PlayerHasWon(board, "X") {
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return NextMove{score: -10 + depth}
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} else if gamecontrol.PlayerHasWon(board, "O") {
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return NextMove{score: 10 - depth}
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} else if gamecontrol.BoardisFull(board) {
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return NextMove{score: 0}
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}
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// check who's turn it is
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if isMaximizingPlayer {
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// set max score
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bestScore := math.MinInt64
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var bestMove NextMove
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// iterate through all fields
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for i := 0; i < 3; i++ {
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for j := 0; j < 3; j++ {
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// check if field is empty
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if board[i][j] == " " {
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// make a move on this field
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board[i][j] = player
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// continue with the other player
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move := Minimax(board, depth+1, false, SwitchPlayer(player))
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// reset the field again
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board[i][j] = " "
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// if this move was better then the move before change values
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if move.score > bestScore {
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bestScore = move.score
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bestMove = NextMove{Row: i, Col: j, score: move.score}
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}
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}
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}
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}
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// return best possible Move
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return bestMove
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} else {
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// set min score
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bestScore := math.MaxInt64
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var bestMove NextMove
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// iterate through all fields
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for i := 0; i < 3; i++ {
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for j := 0; j < 3; j++ {
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// check if field is empty
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if board[i][j] == " " {
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// make a move on this field
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board[i][j] = player
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// continue with the other player
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move := Minimax(board, depth+1, true, SwitchPlayer(player))
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// reset the field again
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board[i][j] = " "
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// if this move was better then the move before change values
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if move.score < bestScore {
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bestScore = move.score
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bestMove = NextMove{Row: i, Col: j, score: move.score}
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}
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}
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}
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}
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// return best possible Move
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return bestMove
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}
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}
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// this function changes the player for the minimax algorthim
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func SwitchPlayer(player string) string {
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if player == "X" {
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return "O"
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} else {
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return "X"
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}
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}
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