poj1840Eqs（hash)

http://poj.org/problem?id=1840

枚举 xi不等0.

View Code

 1 #include <iostream>

 2 #include<cstdio>

 3 #include<cstring>

 4 using namespace std;

 5 #define MOD 97777

 6 #define size 1000010

 7 int t,head[size],next[size],v[size],num[size][2];

 8 void init()

 9 {

10     t =0 ;

11     memset(head,-1,sizeof(head));

12 }

13 void add(int a,int b)

14 {

15     next[t] = head[a];

16     head[a] = t;

17     v[t] = b;

18     t++;

19 }

20 int main()

21 {

22     int i,j,k,a[6],s,g=0;

23     init();

24     for(i = 1; i <= 5 ; i++)

25     cin>>a[i];

26     for(i = -50; i <= 50 ;i++)

27     {

28         if(i==0)

29         continue;

30         for(j = -50; j <= 50 ; j++)

31         {

32             g++;

33             if(j==0)

34             continue;

35             s = a[1]*(i*i*i)+a[2]*(j*j*j);

36             s = s%MOD;

37             if(s<0)

38             s+=MOD;

39             num[g][0] = i;

40             num[g][1] = j;

41             add(s,g);

42         }

43     }

44     int sum = 0,o,ss;

45     for(i = -50 ; i <= 50 ; i++)

46     {

47         if(i==0)

48         continue;

49         for(j = -50 ; j <= 50 ; j++)

50         {

51             if(j==0)

52             continue;

53             for(k = -50 ; k <= 50 ; k++)

54             {

55                 if(k==0)

56                 continue;

57                 s = a[3]*(i*i*i)+a[4]*(j*j*j)+a[5]*(k*k*k);

58                 ss = s;

59                 s = (-s)%MOD;

60                 if(s<0)

61                 s += MOD;

62                 for(o = head[s] ; o!=-1 ; o = next[o])

63                 {

64                     int i1 = num[v[o]][0],i2 = num[v[o]][1];

65                     if((a[1]*(i1*i1*i1)+a[2]*(i2*i2*i2))==-ss)

66                          sum++;

67                 }

68             }

69         }

70     }

71     cout<<sum<<endl;

72     return 0;

73 }