Submission #545114

#TimeUsernameProblemLanguageResultExecution timeMemory
545114leakedMisspelling (JOI22_misspelling)C++14
100 / 100
2440 ms113964 KiB
#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;
}
/*

*/
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