✨ Finit le jour 17

day_17/part_2.php

@@ -0,0 +1,55 @@
+<?php
+
+$input = file_get_contents('./input.txt');
+
+preg_match('/^target area: x=(\d+)\.\.(\d+), y=(-?\d+)\.\.(-?\d+)$/', $input, $matches);
+
+[, $x_min, $x_max, $y_min, $y_max] = $matches;
+$target = ['x_min' => $x_min, 'x_max' => $x_max, 'y_min' => $y_min, 'y_max' => $y_max];
+
+function increment(&$x, &$y, &$x_velocity, &$y_velocity)
+{
+    $current_x = $x;
+    $x += $x_velocity;
+    $y += $y_velocity;
+    if ($x_velocity > 0) $x_velocity -= 1;
+    elseif ($x_velocity < 0) $x_velocity += 1;
+    else $x_velocity = 0;
+    $y_velocity -= 1;
+}
+
+function check($x, $y, $target)
+{
+    return $x >= $target['x_min'] &&
+        $x <= $target['x_max'] &&
+        $y >= $target['y_min'] &&
+        $y <= $target['y_max'];
+}
+
+$x = 0;
+$y = 0;
+$x_velocity = 6;
+$y_velocity = 9;
+
+$possibilities = [];
+for ($i = 0; $i <= abs($target['x_max']); $i++) {
+    for ($j = -abs($target['y_min']); $j <= abs($target['y_min']); $j++) {
+        if ($i === 0 && $j === 0) continue;
+        $x = 0;
+        $y = 0;
+        $x_velocity = $i;
+        $y_velocity = $j;
+        while(!check($x, $y, $target)) {
+            echo sprintf('x: %s, y: %s%s', $x, $y, "\n");
+            increment($x, $y, $x_velocity, $y_velocity);
+            if ($y <= $target['y_min']) {
+                break;
+            }
+        }
+        if (check($x, $y, $target)) {
+            $possibilities[] = sprintf('%s,%s', $i, $j);
+        }
+    }
+}
+
+echo count($possibilities);