## 题：
**如果a+b+c=1000，且a^2+b^2=c^2（a,b,c为自然数），如何求出a、b、c可能的组合？**
枚举法：
```
import time
start_time = time.time()
for a in range(0, 1001):
for b in range(0, 1001):
for c in range(0, 1001):
if a+b+c==1000 and a**2+b**2==c**2:
print("a,b,c:%d,%d,%d" % (a,b,c))
end_time = time.time()
print("time:%0.2f" % (end_time-start_time))
```
优化
```
import time
start_time = time.time()
for a in range(0, 1001):
for b in range(0, 1001):
c = 1000 -a - b
if a**2+b**2==c**2:
print("a,b,c:%d,%d,%d" % (a,b,c))
end_time = time.time()
print("time:%0.2f" % (end_time-start_time))
```
