[Example] Sorting Algorithms (#205)

* Add insertion sort

* Update pr number

Author: pearmini

app/examples/sorting.recho.js

@@ -0,0 +1,90 @@
+/**
+ * @title Sorting Algorithms
+ * @author Bairui Su
+ * @created 2026-01-03
+ * @github pearmini
+ * @pull_request 205
+ * @thumbnail_start 24
+ * @label Algorithm
+ */
+
+/**
+ * ============================================================================
+ * =                            Sorting Algorithms                            =
+ * ============================================================================
+ * Insertion sort is efficient for small arrays. Think of it like playing
+ * cards: you're holding sorted cards in your left hand (sorted prefix/subarray)
+ * and holding a card in your right hand (key). You insert the current card into
+ * the sorted cards until there is no card in the table (unsorted subarray).
+ */
+
+recho.button("Run", run);
+
+//➜ Insertion Sort                          
+//➜                        ▁                
+//➜                     ▃▃▇█▃  ▃   █        
+//➜               ▂▃▃▆▆██████▆ █  ██ ▇ ▁   ▄
+//➜             ▄▅████████████ █ ▅██▇█ █ ▂ █
+//➜      ▁▂▂▃▇████████████████ █▃███████▆█▃█
+//➜ ▁▄▅▆██████████████████████▄█████████████
+visualize(array, insertionSort, "Insertion Sort");
+
+function* insertionSort(array) {
+  for (let i = 1; i < array.length; i++) {
+    const key = array[i];
+    let j = i - 1;
+    while (j >= 0 && array[j] > key) {
+      array[j + 1] = array[j];
+      yield array.slice();
+      j--;
+    }
+    array[j + 1] = key;
+    yield array.slice();
+  }
+  yield array.slice();
+  return array;
+}
+
+const [array, setArray] = recho.state(data());
+
+const chs = ["▁", "▂", "▃", "▄", "▅", "▆", "▇", "█"];
+
+function run() {
+  setArray(data());
+}
+
+function data() {
+  return d3.range(40).map(() => d3.randomInt(1, 100)());
+}
+
+function visualize(array, sorter, label) {
+  const sortedArray = sorter(array);
+  const y = d3.scaleLinear(d3.extent(array), [0, 40]);
+  const timer = setInterval(() => {
+    const step = sortedArray.next();
+    if (step.done) {
+      clearInterval(timer);
+    } else {
+      echo.clear();
+      const len = chs.length;
+      const Y = step.value.map(y).map((d) => {
+        const n = Math.floor(d / len);
+        const r = Math.floor(d - n * len);
+        return chs[len - 1].repeat(n) + chs[r];
+      });
+      const maxHeight = d3.max(Y, (d) => d.length);
+      const padY = Y.map((d) => d.padEnd(maxHeight, " ").split(""));
+      let output = label ? `${label}\n` : "";
+      for (let i = 0; i < maxHeight; i++) {
+        for (let j = 0; j < padY.length; j++) {
+          output += padY[j][maxHeight - i - 1];
+        }
+        output += i < maxHeight - 1 ? "\n" : "";
+      }
+      echo.set("compact", true)(output);
+    }
+  }, 20);
+  echo.dispose(() => clearInterval(timer));
+}
+
+const d3 = recho.require("d3");