Submission #1178334

#TimeUsernameProblemLanguageResultExecution timeMemory
1178334ace5Misspelling (JOI22_misspelling)C++20
100 / 100
277 ms247020 KiB
#include <bits/stdc++.h>

using namespace std;

const int maxn = 500005;
const int mod = 1000000007;
const int maxlog = 19;
const int alf = 26;

int add(int a,int b)
{
    return a+b >= mod ? a+b-mod : a+b;
}

vector<pair<int,int>> st[2];

int dp[2][alf][maxn],pref[alf+1][maxn],suf[alf+1][maxn];
vector<int> r[2][maxn];

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    int n,m;
    cin >> n >> m;
    for(int i = 0;i < m;++i)
    {
        int a,b;
        cin >> a >> b;
        a--;
        b--;
        if(a < b)
            r[1][a].push_back(b-1);
        else
            r[0][b].push_back(a-1);
    }
    int maxr[2][n];
    for(int j = n-1;j >= 0;--j)
    {
        for(int y = 0;y < 2;++y)
        {
            int rg = j-1;
            for(int u = 0;u < r[y][j].size();++u)
            {
                rg = max(rg,r[y][j][u]);
            }
            while(st[y].size() && st[y].back().first <= rg+1)
            {
                rg = max(rg,st[y].back().second);
                st[y].pop_back();
            }
            maxr[y][j] = rg+1;
            if(rg >= j)
                st[y].push_back({j,rg});
        }
    }
    for(int j = n-1;j >= 0;--j)
    {
        for(int c = 0;c < alf;++c)
        {
            for(int y = 0;y < 2;++y)
            {
                if(j == n-1)
                    dp[y][c][j] = 0;
                else
                {
                    if(maxr[y][j] != j)
                        dp[y][c][j] = dp[y][c][maxr[y][j]];
                    else
                    {
                        dp[y][c][j] = add(dp[y][c][j+1],y ? suf[c+1][j+1] : pref[c][j+1]);
                    }
                }
            }
            pref[c+1][j] = add(pref[c][j],add(dp[0][c][j],dp[1][c][j]+1));
        }
        for(int c = alf-1;c >= 0;--c)
            suf[c][j] = add(suf[c+1][j],add(dp[0][c][j],dp[1][c][j]+1));
    }
    cout << pref[alf][0];
}
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