647518391e258e80eedf6e06

src/647518391e258e80eedf6e06.js

@@ -0,0 +1,34 @@
+
+const createTwoSetsOfEqualSum = n => {
+  const all = n * (n+1) / 2;
+  if (all % 2 === 1) return [];
+  const half = all / 2;
+  const a = [];
+  let sum = 0;
+  let skip;
+  let i = n;
+  for (; i > 0; --i) {
+    sum += i;
+    if (sum > half) {
+      sum -= i;
+      skip = half-sum;
+      a.push(skip);
+      break;
+    } else {
+      a.push(i);
+      skip = i;
+      if (sum === half) break;
+    }
+  }
+  const b = [];
+  for (let j = 1; j <= i; ++j) {
+    if (j === skip) continue;
+    b.push(j);
+  }
+  return [a, b];
+};
+
+createTwoSetsOfEqualSum(3);
+createTwoSetsOfEqualSum(8);
+createTwoSetsOfEqualSum(9);
+createTwoSetsOfEqualSum(23);