CSP202104-4校门外的树

`#include

include

include

include

include

include

include

include

include

include

include

include

using namespace std;

define MX Maxn + 5

define LS p<<1

define RS p<<1|1

typedef long long ll;

define rep_(i,a,b) for(int i=(a); i<(b); ++i)

define for_(i,a,b) for(int i=(a); i<=(b); ++i)

define dwn_(i,a,b) for(int i=(a); i>=(b); --i)

inline void chkmax(int &x,int y) {if(x<y) x=y;}

inline void chkmin(int &x,int y) {if(x>y) x=y;}

const int Maxn = 100000;

ll P = 1e9+7, inf = 0x3f3f3f3f;

const ll Inf = 0x3f3f3f3f3f3f3f3fll;

int N, M, T, RT, cnt ;

int a[1005]; ll f[1005]; int vis[100005];

ll cal(int d, int id) {

ll res = 0;

for_(i,1,sqrt(d)) {

if(d % i == 0) {

if(vis[i] != id) ++res,vis[i] = id;

if(vis[d/i] != id) ++res,vis[d/i] = id;

res %= P;

}

}

return (res - 1 + P) % P;

}

int main()

{

cin >> N;

for_(i,1,N) cin >> a[i];

f[1] = 1;
for_(i,1,N)
    dwn_(j, i - 1, 1)
        f[i] = (f[j] * cal(a[i] - a[j], i) % P + f[i]) % P;

cout << f[N];
return 0;

}

`