Codeforces Round #209 (Div. 2)C

刷了一页的WA  。。终于发现了 哪里错了 快速幂模板里一个变量t居然开得long  ...

虽然代码写的丑了点 但是是对的 那个该死的long 啊..

 1 #include <iostream>

 2 #include<cstdio>

 3 #include<cstring>

 4 #include<algorithm>

 5 #include<stdlib.h>

 6 #include<vector>

 7 using namespace std;

 8 #define mod 1000000007

 9 #define LL __int64

10 #define N 100010

11 LL n,x,a[N],s,b[N];

12 LL exp_mod(LL a,LL n,LL b)

13 {

14     long long t;

15     if(n==0) return 1%b;

16     if(n==1) return a%b;

17     t=exp_mod(a,n/2,b);

18     t=t*t%b;

19     if((n&1)==1) t=t*a%b;

20     return t;

21 }

22 int main()

23 {

24     int i;

25     cin>>n>>x;

26     for(i = 1; i <= n ; i++)

27     {

28         scanf("%I64d",&a[i]);

29         s = s+a[i];

30         b[i] = a[i];

31     }

32     for(i = 1; i <= n ; i++)

33     {

34         b[i] = s-a[n-i+1];

35     }

36     for(i = 1; i <= n ;i++)

37     a[i] = b[i];

38     LL k = a[1];

39     int o = 2;LL ss=a[1];

40     LL sum=1;

41     b[2]-=a[1];

42     while(1)

43     {

44         if(b[o]==0&&o<=n)

45         {

46             o++;

47             b[o]-=a[o-1];

48             sum++;

49             if(o>n) break;

50             else

51             continue;

52         }

53         if(o>n) break;

54         if(sum%x!=0) break;

55         while(sum%x==0&&o<=n)

56         {

57             sum/=x;

58             ss++;

59             b[o]--;

60             if(b[o]==0)

61             {

62                 o++;

63                 b[o]-=a[o-1];

64                 sum++;

65                 break;

66             }

67         }

68         if(o>n) break;

69     }

70     while(sum&&sum%x==0)

71     {

72         ss+=1;

73         sum/=x;

74     }

75     printf("%I64d\n",exp_mod(x,min(s,ss),mod));

76     return 0;

77 }

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