提出 #73400289

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ソースコード 拡げる

#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ull = unsigned long long;
using lll = __int128;
using pll = pair<ll, ll>;
#define fi first
#define se second
#define debug(x) cerr << #x << ": " << x << '\n';
const int N = 2e5+10;
const ll MOD = 998244353;
const ll INF = 0x3f3f3f3f3f3f3f3f;

void init(){

}

void solve(){
    ll n,m;
    cin>>n>>m;
    vector<pll> p(m+1);
    for(int i=1;i<=m;++i){
        ll l,r;
        cin>>l>>r;
        p[i]={l,r};
    }
    sort(p.begin()+1,p.end());
    ll rmax=0;
    ll p1=1;
    ll cnt=0;
    while(rmax<n and p1<=m){
        ll tr=0;
        while(p[p1].fi<=rmax+1 and p1<=m){
            // debug(p[p1].fi);
            tr=max(tr,p[p1].se);
            p1++;
        }
        // debug(tr);
        if(tr<=rmax) break;
        else {rmax=tr;cnt++;}
    }
    if(rmax==n){
        cout<<cnt;
    }
    else{
        cout<<-1;
    }
}

int main(){
    ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
    init();
    int _ =1;
    // cin>> _;
    while(_--)
        solve();
    return 0;
}

提出情報

ジャッジ結果