第一次尝试

import time

start_time = time.time()

# 注意是三重循环
for a in range(0, 1001):
    for b in range(0, 1001):
        for c in range(0, 1001):
            if a**2 + b**2 == c**2 and a+b+c == 1000:
                print("a, b, c: %d, %d, %d" % (a, b, c))

end_time = time.time()
print("elapsed: %f" % (end_time - start_time))
print("complete!")

运行结果：

a, b, c: 0, 500, 500
a, b, c: 200, 375, 425
a, b, c: 375, 200, 425
a, b, c: 500, 0, 500
elapsed: 214.583347
complete!

注意运行的时间:214.583347秒