Submission #442157

#	Time	Username	Problem	Language	Result	Execution time	Memory
442157		Haruto810198	Rainforest Jumps (APIO21_jumps)	C++17	0 / 100	26 ms	2916 KiB

jumps

#include <bits/stdc++.h>

using namespace std;

//#define int long long
#define double long double

#define FOR(i,l,r,d) for(int i=(l);i<=(r);i+=(d))
#define szof(x) ((int)(x).size())

#define vi vector<int>
#define pii pair<int,int>

#define F first
#define S second

#define pb push_back
#define eb emplace_back
#define mkp make_pair

#define V st[cidx]
#define LC st[cidx*2]
#define RC st[cidx*2+1]
#define lsb(x) ((x)&(-(x)))

//const int INF = 2147483647;
//const int LNF = INF*INF;
const int INF = 1000000007;
const int MOD = 1000000007;
const int mod = 998244353;
const double eps = 1e-12;

//#pragma GCC optimize("Ofast")
//#pragma GCC optimize("unroll-loops")

const int MAX = 200010;
const int lgMAX = 20;

int n;
int h[MAX];
int edge_l[MAX], edge_r[MAX];
int anc_l[MAX][lgMAX];
int anc_hi[MAX][lgMAX], anc_lo[MAX][lgMAX];
int Max[MAX][lgMAX];
int dest_Max;

int query_Max(int L, int R){ /// [L, R]
    int ret = -INF;
    FOR(i, L, R, 1){
        ret = max(ret, h[i]);
    }
    return ret;
    //int len = R - L + 1;
    //int lglen = __lg(len);
    //return max(Max[L][lglen], Max[R - (1<<lglen) + 1][lglen]);
}

int get_start(int A, int B){
    int ret = B;
    for(int j=lgMAX-1; j>=0; j--){
        if( anc_l[ret][j] != INF and h[anc_l[ret][j]] < dest_Max and anc_l[ret][j] >= A ){
            ret = anc_l[ret][j];
        }
    }
    return ret;
}

pii jump_hi(int v){
    int ret = 0;
    for(int j=lgMAX-1; j>=0; j--){
        if( anc_hi[v][j] != INF and h[anc_hi[v][j]] <= dest_Max ){
            v = anc_hi[v][j];
            ret += (1<<j);
        }
    }
    return mkp(v, ret);
}

int jump_lo(int v){
    int ret = 0;
    for(int j=lgMAX-1; j>=0; j--){
        if( anc_lo[v][j] != INF and h[anc_lo[v][j]] <= dest_Max ){
            v = anc_lo[v][j];
            ret += (1<<j);
        }
    }
    if( h[v] > dest_Max ){
        ret = INF;
    }
    if( h[v] < dest_Max and ( anc_lo[v][0] == INF or h[anc_lo[v][0]] > dest_Max ) ){
        ret = INF;
    }
    return ret;
}

void init(int N, vi H){

    //
    assert(N <= 2000);
    //

    /// input
    n = N;
    FOR(i, 0, n-1, 1){
        h[i] = H[i];
    }

    /// monotonic stack
    FOR(i, 0, n-1, 1){
        edge_l[i] = INF; /// INF -> no edge
        edge_r[i] = INF;
    }

    vi stk;
    FOR(i, 0, n-1, 1){

        while(!stk.empty() and h[stk.back()] < h[i]){
            stk.pop_back();
        }

        if(!stk.empty()){
            edge_l[i] = stk.back();
        }
        stk.pb(i);

    }

    stk.clear();

    for(int i=n-1; i>=0; i--){

        while(!stk.empty() and h[stk.back()] < h[i]){
            stk.pop_back();
        }

        if(!stk.empty()){
            edge_r[i] = stk.back();
        }
        stk.pb(i);

    }

    /// 2^k-th ancestor
    FOR(i, 0, n-1, 1){
        if(edge_l[i]==INF and edge_r[i]==INF){
            anc_hi[i][0] = INF;
            anc_lo[i][0] = INF;
        }
        else if(edge_l[i]==INF or edge_r[i]==INF){
            anc_hi[i][0] = INF;
            anc_lo[i][0] = min(edge_l[i], edge_r[i]);
        }
        else{
            anc_hi[i][0] = (h[edge_l[i]] > h[edge_r[i]]) ? edge_l[i] : edge_r[i];
            anc_lo[i][0] = (h[edge_l[i]] < h[edge_r[i]]) ? edge_l[i] : edge_r[i];
        }
        anc_l [i][0] = edge_l[i];
    }
    FOR(j, 1, lgMAX-1, 1){
        FOR(i, 0, n-1, 1){
            anc_hi[i][j] = (anc_hi[i][j-1]!=INF) ? anc_hi[ anc_hi[i][j-1] ][j-1] : INF;
            anc_lo[i][j] = (anc_lo[i][j-1]!=INF) ? anc_lo[ anc_lo[i][j-1] ][j-1] : INF;
            anc_l [i][j] = (anc_l [i][j-1]!=INF) ? anc_l [ anc_l [i][j-1] ][j-1] : INF;
        }
    }

    /// sparse table for Max query
    FOR(i, 0, n-1, 1){
        Max[i][0] = h[i];
    }
    FOR(j, 1, lgMAX-1, 1){
        FOR(i, 0, n-1, 1){
            if(i + (1<<j-1) <= n-1){
                Max[i][j] = max(Max[i][j-1], Max[i + (1<<j-1)][j-1]);
            }
            else{
                Max[i][j] = Max[i][j-1];
            }
        }
    }

}

int minimum_jumps(int A, int B, int C, int D){

    dest_Max = query_Max(C, D);
    //cerr<<"dest_Max = "<<dest_Max<<endl;

    int start = get_start(A, B);
    //cerr<<"start = "<<start<<endl;

    int v = start, res;

    pii tmp = jump_hi(start);
    v = tmp.F;
    res = tmp.S;
    //cerr<<"jump_hi : v = "<<tmp.F<<", res += "<<tmp.S<<endl;

    res += jump_lo(v);
    //cerr<<"jump_lo : res += "<<jump_lo(v)<<endl;

    //cerr<<"res = "<<res<<endl;

    if(res < INF){
        return res;
    }
    else{
        return -1;
    }

}

/*
signed main(){

    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);

    init(7, {3, 2, 1, 6, 4, 5, 7});

    cerr<<minimum_jumps(4, 4, 6, 6)<<endl; /// 2
    cerr<<minimum_jumps(1, 3, 5, 6)<<endl; /// 1
    cerr<<minimum_jumps(0, 1, 2, 2)<<endl; /// -1

    return 0;

}
*/

Compilation message (stderr)

jumps.cpp: In function 'void init(int, std::vector<int>)':
jumps.cpp:173:25: warning: suggest parentheses around '-' inside '<<' [-Wparentheses]
  173 |             if(i + (1<<j-1) <= n-1){
      |                        ~^~
jumps.cpp:174:59: warning: suggest parentheses around '-' inside '<<' [-Wparentheses]
  174 |                 Max[i][j] = max(Max[i][j-1], Max[i + (1<<j-1)][j-1]);
      |                                                          ~^~

• Subtask 1: 0 / 4
• Subtask 2: 0 / 8
• Subtask 3: 0 / 13
• Subtask 4: 0 / 12
• Subtask 5: 0 / 23
• Subtask 6: 0 / 21
• Subtask 7: 0 / 19