Submission #577968

#	Time	Username	Problem	Language	Result	Execution time	Memory
577968		Theo830	Ancient Books (IOI17_books)	C++17	0 / 100	12 ms	17452 KiB

books

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll INF = 1e9;
ll MOD = 998244353;
typedef pair<ll,ll> ii;
#define iii pair<int,int>
#define f(i,a,b) for(ll i = a;i < b;i++)
#define pb push_back
#define vll vector<ll>
#define F first
#define S second
#define all(x) (x).begin(), (x).end()
///I hope I will get uprating and don't make mistakes
///I will never stop programming
///sqrt(-1) Love C++
///Please don't hack me
///@TheofanisOrfanou Theo830
///Think different approaches (bs,dp,greedy,graphs,shortest paths,mst)
///Stay Calm
///Look for special cases
///Beware of overflow and array bounds
///Think the problem backwards
///Training
///Dremix10 's template
const int N = 2e3+1;
template<typename T>
struct SPARSE{
    vector<vector<T> > sparse;
    vector<int> log;
    const int maxPow = 22;
    int N;

    void init(int n){
        sparse.assign(n,vector<T>(maxPow));
        log.assign(n+1,0);
        N = n;

        for(int i = 2;i <= n;i++)
            log[i] = log[i/2] + 1;
    }

    // supports 0-indexing
    void build(T arr[]){
        int i,j;
        for(i = 0;i < N ;i++)
            sparse[i][0] = arr[i];

        for(j = 1;j < maxPow;j++)
            for(i = 0;i + (1<<j) <= N;i++)
                sparse[i][j] = min(sparse[i][j-1],sparse[i+(1<<(j-1))][j-1]);
    }

    T query(int l, int r){
        int k = log[r-l+1];
        return min(sparse[l][k],sparse[r-(1<<k)+1][k]);
    }

};
template<typename T>
struct SPARSE2{
    vector<vector<T> > sparse;
    vector<int> log;
    const int maxPow = 22;
    int N;

    void init(int n){
        sparse.assign(n,vector<T>(maxPow));
        log.assign(n+1,0);
        N = n;

        for(int i = 2;i <= n;i++)
            log[i] = log[i/2] + 1;
    }

    // supports 0-indexing
    void build(T arr[]){
        int i,j;
        for(i = 0;i < N ;i++)
            sparse[i][0] = arr[i];

        for(j = 1;j < maxPow;j++)
            for(i = 0;i + (1<<j) <= N;i++)
                sparse[i][j] = max(sparse[i][j-1],sparse[i+(1<<(j-1))][j-1]);
    }

    T query(int l, int r){
        int k = log[r-l+1];
        return max(sparse[l][k],sparse[r-(1<<k)+1][k]);
    }

};
SPARSE<ll>S;
SPARSE2<ll>s2;
#include "books.h"
ll dp[1005][1005];
ll n;
ll Left[1005];
ll Right[1005];
ll solve(ll i,ll j){
    if(i == 0 && j == n-1){
        return 0;
    }
    if(dp[i][j] != -1){
        return dp[i][j];
    }
    ll L = S.query(i,j),R = s2.query(i,j);
    if(i == L && j == R){
        ll ans = min(solve(i + 1,j) + 2,solve(i,j + 1) + 2);
        return dp[i][j] = ans;
    }
    return dp[i][j] = solve(L,R);
}
long long minimum_walk(std::vector<int> p, int s) {
    ll ans = 0;
    n = p.size();
    bool v[n] = {0};
    ll dist = 0;
    ll l[n],r[n];
    ll L = -1,R;
    vector<ii>rang;
    if(p[s] == s){
        L = R = s;
        rang.pb(ii(s,s));
    }
    f(i,0,n){
        Left[i] = n;
    }
    f(i,0,n){
        if(p[i] != i && !v[i]){
            ll last = i;
            ll st = i;
            ll pos = p[i];
            v[i] = 1;
            l[st] = i,r[st] = pos;
            while(pos != st){
                l[st] = min(l[st],pos);
                r[st] = max(r[st],pos);
                v[pos] = 1;
                ans += abs(pos - last);
                last = pos;
                pos = p[pos];
            }
            ans += abs(pos - last);
            l[st] = min(l[st],pos);
            r[st] = max(r[st],pos);
            rang.pb(ii(l[st],r[st]));
            if(v[s] == 1 && L == -1){
                L = l[st];
                R = r[st];
            }
        }
    }
    if(rang.empty()){
        return ans;
    }
    for(auto x:rang){
        Left[x.S] = min(Left[x.S],x.F);
        Right[x.F] = max(Right[x.F],x.S);
    }
    S.init(n);
    s2.init(n);
    S.build(Left);
    s2.build(Right);
    memset(dp,-1,sizeof dp);
    assert(L == 0);
    dist = solve(L,R);
    ans += dist;
    return ans;
}
/*
int main() {
    int n, s;
    assert(2 == scanf("%d %d", &n, &s));

    vector<int> p((unsigned) n);
    for(int i = 0; i < n; i++)
        assert(1 == scanf("%d", &p[(unsigned) i]));

    long long res = minimum_walk(p, s);
    printf("%lld\n", res);

    return 0;
}
*/
/*
4 0
0 2 3 1
*/

Compilation message (stderr)

books.cpp: In function 'long long int minimum_walk(std::vector<int>, int)':
books.cpp:120:15: warning: 'R' may be used uninitialized in this function [-Wmaybe-uninitialized]
  120 |     ll L = -1,R;
      |               ^

• Subtask 1: 0 / 12
• Subtask 2: 0 / 10
• Subtask 3: 0 / 28
• Subtask 4: 0 / 20
• Subtask 5: 0 / 30