下面 count_triple 函数的时间复杂度为(    )。

int count_triple(int n) {

int cnt = 0;

for (int a = 1; a <= n; a++)

for (int b = a; a + b <= n; b++) {

int c = sqrt(a * a + b * b);

if (a + b + c > n)

break;

if (a * a + b * b == c * c)

cnt++;

}

return cnt;

}