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feat: 2588. Count the Number of Beautiful Subarrays, 前缀和+hash

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	`1`	`+/**`
	`2`	`+ * @param {number[]} nums`
	`3`	`+ * @return {number}`
	`4`	`+`
	`5`	`+3, 1, 2 => 11, 01, 10`
	`6`	`+4, 3, 1, 2, 4 => 100, 11, 01, 10, 100`
	`7`	`+满足条件的子数组:每一位上 1 出现的次数为偶数次,异或结果为 0`
	`8`	`+异或结果 <= 10^6,因此可以存储下 map[异或结果] = 前面的出现次数`
	`9`	`+ */`
	`10`	`+var beautifulSubarrays = function(nums) {`
	`11`	`+ let mp = {}, n = nums.length, xor = 0, ans = 0`
	`12`	`+ mp[0] = 1`
	`13`	`+ for (let i = 0; i < n; i++) {`
	`14`	`+ xor ^= nums[i]`
	`15`	`+ ans += mp[xor] ?? 0`
	`16`	`+ mp[xor] ??= 0`
	`17`	`+ mp[xor]++`
	`18`	`+ }`
	`19`	`+ return ans`
	`20`	`+};`

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