[examples] A tic-tac-toe app.

examples/tictactoe/.gitignore

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+outputs/
+build/

examples/tictactoe/README.md

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+# tictactoe.aleo
+
+## Build Guide
+
+To compile this Aleo program, run:
+```bash
+aleo build
+```

examples/tictactoe/inputs/tictactoe.in

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+// The program input for tictactoe/src/main.leo
+[main]
+public player: u8 = 1u8;
+row: u8 = 1u8;
+col: u8 = 1u8;
+board = Board {
+    c11: 0u8,
+    c12: 0u8,
+    c13: 0u8,
+    c21: 0u8,
+    c22: 0u8,
+    c23: 0u8,
+    c31: 0u8,
+    c32: 0u8,
+    c33: 0u8
+}

examples/tictactoe/program.json

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+{
+    "program": "tictactoe.aleo",
+    "version": "0.0.0",
+    "description": "",
+    "development": {
+        "private_key": "APrivateKey1zkp9VmTEpkumnHuyA7EcQDspf4rPbHnqYxkXHBewDR9xf86",
+        "address": "aleo1ygel5r0p5a77dfvheypqq5ylq6ha2k0qm3k08wpddnx6pqmr6sgs496asf"
+    },
+    "license": "MIT"
+}

examples/tictactoe/src/main.leo

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+// This will work better with arrays, but for now we just expand the 9 cells.
+circuit Board {
+    // c(ell){row}{column} (0 for empty, 1 for X, 2 for O):
+    c11: u8,
+    c12: u8,
+    c13: u8,
+    c21: u8,
+    c22: u8,
+    c23: u8,
+    c31: u8,
+    c32: u8,
+    c33: u8
+}
+
+function win(b: Board, p: u8) -> bool {
+    return
+        (b.c11 == p && b.c12 == p && b.c13 == p) || // row 1
+        (b.c21 == p && b.c22 == p && b.c23 == p) || // row 2
+        (b.c31 == p && b.c32 == p && b.c33 == p) || // row 3
+        (b.c11 == p && b.c21 == p && b.c31 == p) || // column 1
+        (b.c12 == p && b.c22 == p && b.c32 == p) || // column 2
+        (b.c13 == p && b.c23 == p && b.c33 == p) || // column 3
+        (b.c11 == p && b.c22 == p && b.c33 == p) || // diagonal
+        (b.c13 == p && b.c22 == p && b.c31 == p); // other diagonal
+}
+
+// This carries out a single move: a player (1 for X, 2 for O) marking a cell.
+// The cell must be empty (i.e. contain 0), otherwise this is a no-op.
+// The u8 result is the winning player, of 0 if there is no winner (yet).
+function main(public player: u8, row: u8, col: u8, board: Board) -> (Board, u8) {
+    console.assert(player == 1u8 || player == 2u8); // 1 for X, 2 for O
+    console.assert(1u8 <= row && row <= 3u8);
+    console.assert(1u8 <= col && col <= 3u8);
+    let new: Board = board;
+    // This will work better when circuit assignment is supported.
+    if row == 1u8 && col == 1u8 && new.c11 == 0u8 {
+        new = Board {
+            c11: player,
+            c12: new.c12,
+            c13: new.c13,
+            c21: new.c21,
+            c22: new.c22,
+            c23: new.c23,
+            c31: new.c31,
+            c32: new.c32,
+            c33: new.c33,
+        };
+    } else if row == 1u8 && col == 2u8 && new.c12 == 0u8 {
+        new = Board {
+            c11: new.c11,
+            c12: player,
+            c13: new.c13,
+            c21: new.c21,
+            c22: new.c22,
+            c23: new.c23,
+            c31: new.c31,
+            c32: new.c32,
+            c33: new.c33,
+        };
+    } else if row == 1u8 && col == 3u8 && new.c13 == 0u8 {
+        new = Board {
+            c11: new.c11,
+            c12: new.c12,
+            c13: player,
+            c21: new.c21,
+            c22: new.c22,
+            c23: new.c23,
+            c31: new.c31,
+            c32: new.c32,
+            c33: new.c33,
+        };
+    } else if row == 2u8 && col == 1u8 && new.c21 == 0u8 {
+        new = Board {
+            c11: new.c11,
+            c12: new.c12,
+            c13: new.c13,
+            c21: player,
+            c22: new.c22,
+            c23: new.c23,
+            c31: new.c31,
+            c32: new.c32,
+            c33: new.c33,
+        };
+    } else if row == 2u8 && col == 2u8 && new.c22 == 0u8 {
+        new = Board {
+            c11: new.c11,
+            c12: new.c12,
+            c13: new.c13,
+            c21: new.c21,
+            c22: player,
+            c23: new.c23,
+            c31: new.c31,
+            c32: new.c32,
+            c33: new.c33,
+        };
+    } else if row == 2u8 && col == 3u8 && new.c23 == 0u8 {
+        new = Board {
+            c11: new.c11,
+            c12: new.c12,
+            c13: new.c13,
+            c21: new.c21,
+            c22: new.c22,
+            c23: player,
+            c31: new.c31,
+            c32: new.c32,
+            c33: new.c33,
+        };
+    } else if row == 3u8 && col == 1u8 && new.c31 == 0u8 {
+        new = Board {
+            c11: new.c11,
+            c12: new.c12,
+            c13: new.c13,
+            c21: new.c21,
+            c22: new.c22,
+            c23: new.c23,
+            c31: player,
+            c32: new.c32,
+            c33: new.c33,
+        };
+    } else if row == 3u8 && col == 2u8 && new.c32 == 0u8 {
+        new = Board {
+            c11: new.c11,
+            c12: new.c12,
+            c13: new.c13,
+            c21: new.c21,
+            c22: new.c22,
+            c23: new.c23,
+            c31: new.c31,
+            c32: player,
+            c33: new.c33,
+        };
+    } else if row == 3u8 && col == 3u8 && new.c33 == 0u8 {
+        new = Board {
+            c11: new.c11,
+            c12: new.c12,
+            c13: new.c13,
+            c21: new.c21,
+            c22: new.c22,
+            c23: new.c23,
+            c31: new.c31,
+            c32: new.c32,
+            c33: player,
+        };
+    }
+    if win(new, 1u8) {
+        return (new, 1u8);
+    } else if win(new, 2u8) {
+        return (new, 2u8);
+    } else {
+        return (new, 0u8);
+    }
+}