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export default function numIdenticalPairs(nums: number[]): number {    const cnt = new Map<number, number>();    for (const num of nums) {        cnt.set(num, (cnt.get(num) ?? 0) + 1);    }    const ans = Array.from(cnt.values()).reduce(        (a, v) => a + Math.floor((v * (v - 1)) / 2),        0,    );    return ans;}