1925：统计平方和三元组的数目（1323 分）

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class Solution:
    def countTriples(self, n: int) -> int:
        res = 0
        for a in range(1,n+1):
            for b in range(1,n+1):
                c = isqrt(a*a+b*b+1)
                if c<=n and c*c==a*a+b*b:
                    res += 1
        return res

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class Solution:
    def countTriples(self, n: int) -> int:
        res = 0
        u = 3
        while u*u<=n*2:
            v = 1
            while v<u and u*u+v*v<=n*2:
                if gcd(v,u)==1:
                    res += n*2//(u*u+v*v)
                v += 2
            u += 2
        return res*2