add: 只出现一次的数字等

src/array/majority-element.js

@@ -0,0 +1,14 @@
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+export const majorityElement = function (nums) {
+  if (nums.length === 1) return nums[0]
+  const tmp = nums.sort((a, b) => a - b)
+  const res = tmp[~~(nums.length / 2)]
+  if (nums.length > 2) return res
+  if (nums.length === 2 && nums[0] === nums[1]) {
+    return res
+  }
+  return -1
+}