Submission #1201192

#	Time	Username	Problem	Language	Result	Execution time	Memory
1201192		browntoad	Rainforest Jumps (APIO21_jumps)	C++20	100 / 100	488 ms	77956 KiB

jumps

#include "jumps.h"
#include <bits/stdc++.h>
using namespace std;
#define ll long long
// #define int ll
#define FOR(i, a, b) for (int i = (a); i < (b); i++)
#define REP(i, n) FOR(i, 0, n) 
#define REP1(i, n) FOR(i, 1, n+1)
#define RREP(i, n) for (int i = (n)-1; i >= 0; i--)
#define pii pair<int, int>
#define f first
#define s second
#define pb push_back
#define ALL(x) (x).begin(), (x).end()
#define SZ(x) (int)((x).size())

namespace{
    const ll maxn = 2e5+5;
    const ll mxpw = 19;
    int smaxR[maxn][mxpw];
    int smaxL[maxn][mxpw];
    int jumpR[maxn][mxpw];

    int ML[maxn][mxpw]; // where i jump to, most left
    int MR[maxn][mxpw];
    vector<int> h(maxn);
    int n;
}

void init(int N, std::vector<int> H) {
    n = N;
    REP(i, n) h[i] = H[i];
    
    REP(i, n){
        smaxL[i][0] = H[i];
        REP1(j, mxpw-1){
            smaxL[i][j] = max(smaxL[i][j-1], smaxL[max(0, i-(1<<j-1))][j-1]);
        }
    }
    RREP(i, n){
        smaxR[i][0] = H[i];
        REP1(j, mxpw-1){
            smaxR[i][j] = max(smaxR[i][j-1], smaxR[min(n-1, i+(1<<j-1))][j-1]);
        }
    }

    stack<int> st;
    RREP(i, n){
        while(SZ(st) && h[st.top()] < h[i]) st.pop();
        if (!SZ(st)){
            MR[i][0] = i; // itself
            jumpR[i][0] = i;
        }
        else{
            MR[i][0] = st.top();
            jumpR[i][0] = st.top();
        }
        st.push(i);
    }
    while(SZ(st)) st.pop();
    REP(i, n){
        while(SZ(st) && h[st.top()] < h[i]) st.pop();
        if (!SZ(st)){
            ML[i][0] = i; // itself
        }
        else{
            ML[i][0] = st.top();
        }
        st.push(i);
    }

    REP1(j, mxpw-1){
        RREP(i, n){
            MR[i][j] = max(MR[MR[i][j-1]][j-1], MR[ML[i][j-1]][j-1]);
            jumpR[i][j] = jumpR[jumpR[i][j-1]][j-1];
        }
        REP(i, n){
            ML[i][j] = min(ML[ML[i][j-1]][j-1], ML[MR[i][j-1]][j-1]);
        }
    }
}

int mxH(int l, int r){
    if (l > r) return 0;
    int p = 31-__builtin_clz(r-l+1);
    return max(smaxR[l][p], smaxL[r][p]);
}


int minimum_jumps(int A, int B, int C, int D){
    if (h[B] > mxH(C, D)) return -1;
    if (mxH(B+1, C-1) > mxH(C, D)) return -1;
    int mxCD = mxH(C, D);

    int l = A, r = B;
    while(l < r){
        int mid = l+r>>1;
        if (mxH(mid, B) < mxCD) r = mid;
        else l = mid+1;
    }
    int tmp = mxH(l, B);
    r = B;
    while(l < r){
        int mid = l+r+1>>1;
        if (mxH(mid, B) == tmp) l = mid;
        else r = mid-1;
    }

    int cnt = 1;
    int curL = l, curR = l;

    int cntbust = 0;
    RREP(i, mxpw){
        int tmpL = min(ML[curL][i], ML[curR][i]);
        int tmpR = max(MR[curL][i], MR[curR][i]);
        if (mxH(tmpL, tmpL) < mxCD){
            cntbust += (1<<i);
            curL = tmpL; curR = tmpR;
        }
    }
    if (curR >= C){ // sometime before, already ok
        curL = l; curR = l;
        RREP(i, mxpw){
            int tmpL = min(ML[curL][i], ML[curR][i]);
            int tmpR = max(MR[curL][i], MR[curR][i]);
            if (tmpR < C){
                cnt += (1<<i);
                curL = tmpL; curR = tmpR;
            }
        }
        return cnt;
    }
    // else, a sequence jumping to left is a waste of time
    cnt = cntbust+1;
    curR = max(MR[curR][0], MR[curL][0]);
    if (curR >= C) return cnt;

    RREP(i, mxpw){
        int tmpR = jumpR[curR][i];
        if (tmpR < C){
            curR = tmpR;
            cnt += (1<<i);
        }
    }
    cnt++;

    return cnt;
}
/*
14 1
13 8 6 5 4 3 0 1 2 7 10 11 12 14
6 6 13 13

11 1
100 5 4 3 2 1 6 7 8 9 10
1 5 10 10
*/

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