提出 #47373650

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ソースコード 拡げる

//vanitas vanitatum et omnia vanitas
#include<bits/stdc++.h>
#define fi first
#define se second
#define eb emplace_back
#define mp make_pair
using namespace std;
typedef long double ld;
typedef long long ll;
typedef unsigned long long ull;
typedef __int128 i128;
template<typename T,typename U>
T ceil(T x, U y) {return (x>0?(x+y-1)/y:x/y);}
template<typename T,typename U>
T floor(T x, U y) {return (x>0?x/y:(x-y+1)/y);}
template<class T,class S>
bool chmax(T &a,const S b) {return (a<b?a=b,1:0);}
template<class T,class S>
bool chmin(T &a,const S b) {return (a>b?a=b,1:0);}
int popcnt(int x) {return __builtin_popcount(x);}
int popcnt(ll x)  {return __builtin_popcountll(x);}
int topbit(int x) {return (x==0?-1:31-__builtin_clz(x));}
int topbit(ll x)  {return (x==0?-1:63-__builtin_clzll(x));}
int lowbit(int x) {return (x==0?-1:__builtin_ctz(x));}
int lowbit(ll x)  {return (x==0?-1:__builtin_ctzll(x));}

#define int long long
#define rep(i,a,b) for(int i=(a);i<=(b);i++)
#define per(i,a,b) for(int i=(a);i>=(b);i--)
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<pii> vp;
typedef tuple<int,int,int> tiii;
int read() {
  int x=0,w=1; char c=getchar(); 
  while(!isdigit(c)) {if(c=='-') w=-1; c=getchar();}
  while(isdigit(c)) {x=x*10+(c-'0'); c=getchar();}
  return x*w;
}

const int N=3005,mod=1e9+7,inv2=(mod+1)/2;
int n,m,x[N],y[N],f[N][N],g[N][N],p[N];

signed main() {
  n=read(), m=read();
  rep(i,1,n) p[i]=read();
  rep(i,1,m) x[i]=read(), y[i]=read();
  rep(i,1,n) rep(j,1,i-1) f[i][j]=1;
  per(i,m,1) {
    int a=x[i], b=y[i];
    rep(i,1,n) g[i][a]=g[a][i]=g[i][b]=g[b][i]=0;
    rep(i,1,n) if(i!=a&&i!=b) {
      g[a][i]=(g[a][i]+f[b][i])%mod;
      g[b][i]=(g[b][i]+f[a][i])%mod;
      g[i][a]=(g[i][a]+f[i][b])%mod;
      g[i][b]=(g[i][b]+f[i][a])%mod;
    }
    g[a][b]=(g[a][b]+f[b][a])%mod;
    g[b][a]=(g[b][a]+f[a][b])%mod;
    rep(i,1,n) if(i!=a&&i!=b) {
      f[a][i]=(f[a][i]+g[a][i])*inv2%mod;
      f[b][i]=(f[b][i]+g[b][i])*inv2%mod;
      f[i][a]=(f[i][a]+g[i][a])*inv2%mod;
      f[i][b]=(f[i][b]+g[i][b])*inv2%mod;
    }
    f[a][b]=(f[a][b]+g[a][b])*inv2%mod;
    f[b][a]=(f[b][a]+g[b][a])*inv2%mod;
  }
  int ans=0;
  rep(i,1,n) rep(j,1,n) if(p[i]<p[j]) ans=(ans+f[i][j])%mod;
  rep(i,1,m) ans=ans*2%mod;
  printf("%lld\n",ans);
  return 0;
}

提出情報

ジャッジ結果