This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include <bits/stdc++.h>
#define f first
#define s second
#define m_p make_pair
#define all(x) (x).begin(),(x).end()
#define rall(x) (x).rbegin(),(x).rend()
#define vec vector
#define pb push_back
#define sz(x) (int)(x).size()
#define pw(x) (1LL<<(x))
#define fast_resp ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
typedef long double ld;
typedef pair<int,ll> pil;
template<class T> bool umin(T &a,const T &b){return (a>b?a=b,1:0);}
template<class T> bool umax(T &a,const T &b){return (a<b?a=b,1:0);}
const int M=1e9+7;
const int N=5e5+1;
void add(int &a,int b){
a+=b;
if(a>=M) a-=M;
else if(a<0) a+=M;
}
int mult(int a,int b){
return 1ll*a*b%M;
}
int dp[N][26];
set<pii> st[2];
vec<array<int,3>> del[N];
vec<array<int,3>> addt[N];
//set<int> st[2];
signed main(){
fast_resp;
int n,m;
cin>>n>>m;
for(int i=0;i<m;i++){
int l,r;
cin>>l>>r;--l;--r;
if(l<r){
++l;addt[l].pb({0,l,i}),del[r+1].pb({0,l,i});
}
else{
if(l==r) continue;
swap(l,r);++l;
addt[l].pb({1,l,i}),del[r+1].pb({1,l,i});
}
}
for(int i=0;i<26;i++) dp[1][i]=1;
for(int i=1;i<n;i++){
for(auto &z : addt[i]) st[z[0]].insert({z[1],z[2]});
for(auto &z : del[i]) st[z[0]].erase({z[1],z[2]});
for(int j=0;j<26;j++){
for(int k=0;k<26;k++){
add(dp[i+1][k],dp[i][j]);
}
}
if(sz(st[0])){
for(int j=0;j<26;j++){
for(int k=j+1;k<26;k++){
add(dp[i+1][j],-dp[st[0].rbegin()->f][k]);
}
}
}
if(sz(st[1])){
for(int j=0;j<26;j++){
for(int k=0;k<j;k++){
add(dp[i+1][j],-dp[st[1].rbegin()->f][k]);
}
}
}
// for(int j=0;j<26;j++){
// cout<<"HEY "<<i+1<<' '<<j<<' '<<dp[i+1][j]<<endl;
// }
}
int ans=0;
for(int j=0;j<26;j++)
add(ans,dp[n][j]);
cout<<ans;
return 0;
}
/*
*/
# | Verdict | Execution time | Memory | Grader output |
---|
Fetching results... |
# | Verdict | Execution time | Memory | Grader output |
---|
Fetching results... |
# | Verdict | Execution time | Memory | Grader output |
---|
Fetching results... |
# | Verdict | Execution time | Memory | Grader output |
---|
Fetching results... |
# | Verdict | Execution time | Memory | Grader output |
---|
Fetching results... |