The Deaf Rats of Hamelin

the-deaf-rats-of-hamelin/index.js

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+// https://www.codewars.com/kata/the-deaf-rats-of-hamelin/javascript
+
+const countDeafRats = function(town) {
+  const [l, r] = town.split('P');
+  const cnt = s => {
+    const c = [0, 0];
+    const p = ['O~', '~O'];
+    while (1) {
+      let idx = p.map(p => s.indexOf(p));
+      let min = Math.min(...idx);
+      let max = Math.max(...idx);
+      let sidx;
+      if (0 <= min) {
+        sidx = min;
+      } else if (0 <= max) {
+        sidx = max;
+      } else {
+        break;
+      }
+      const sp = s.slice(sidx, sidx+2);
+      s = s.replace(sp, '');
+      ++c[p.indexOf(sp)];
+    }
+    return c;
+  };
+  return cnt(l)[0] + cnt(r)[1];
+};