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