在python中使用全局变量

我是python的新手。 我试图将我的一个C程序转换为相应的python程序，但是我无法在python中使用全局变量。 我在c和python中的代码是：

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#include  int globalcount; void noofways(int firstnumchosen,int sum,int numofnum) { if(sum<0) return; if(sum==0 && numofnum!=0) return; if(sum==0 && numofnum==0){ globalcount++; return; } if(numofnumsum) return; noofways(firstnumchosen+1,sum,numofnum); noofways(firstnumchosen+1,sum-firstnumchosen,numofnum-1); } int main() { noofways(1,8,3); printf("Required number: %d",globalcount); return 0; } 

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 def noofways(firstnumchosen, sum, numofnum): global count count=0 if sum<0: return if sum==0 and not(numofnum==0): return if sum==0 and numofnum==0: count+=1 return if numofnumsum: return noofways(firstnumchosen+1,sum,numofnum) noofways(firstnumchosen+1,sum-firstnumchosen,numofnum-1) res=noofways(1,8,3); print count 

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我想我知道如何在python中声明一个全局变量，但我在弄清楚如何将该变量与递归一起使用时遇到了问题。

Answer 1

每次递归调用都会将计数设置回0

 def noofways(firstnumchosen, sum, numofnum): global count # don't set count to 0 here if sum<0: return if sum==0 and not(numofnum==0): return if sum==0 and numofnum==0: count+=1 return if numofnum<=0: return if firstnumchosen>sum: return noofways(firstnumchosen+1,sum,numofnum) noofways(firstnumchosen+1,sum-firstnumchosen,numofnum-1) # set count to 0 here count = 0 res=noofways(1,8,3); print count