Submission #415886

#	Time	Username	Problem	Language	Result	Execution time	Memory
415886		A_D	Rainforest Jumps (APIO21_jumps)	C++14	48 / 100	1656 ms	56828 KiB

jumps

#include "jumps.h"

#include <bits/stdc++.h>

using namespace std;
const int NN=2e5+100;
const int L=18;
const int INF=1e9;
int a[NN],lo[NN];
bool vis[NN];
int seg[4*NN];
int n;
vector<int> g[NN];
vector<int> vec;
int st[NN][L][2];
int stt[NN][L];
void build()
{
    lo[1]=0;
    for(int i=2;i<=n+1;i++){
        lo[i]=lo[i/2]+1;
    }
	for (int j=1;j<L;j++){
        for (int i=0;i+(1 << j)<=n;i++){
            stt[i][j]=max(stt[i][j-1],stt[i+(1<<(j-1))][j-1]);
        }
    }
}

int get(int L,int R)
{
    if(R<L)assert(0);
    int j = lo[R - L + 1];
    int ret=max(stt[L][j], stt[R - (1 << j) + 1][j]);
    return ret;
}

void init(int N, std::vector<int> H) {
    n=N;
    for(int i=0;i<L;i++){
        st[n+1][i][0]=n+1;
        st[n+1][i][1]=n+1;
    }
    for(int i=0;i<N;i++){
        a[i]=H[i];
        stt[i][0]=a[i];
    }
    build();
    for(int i=0;i<n;i++){
        if(i!=n-1&&get(i,n-1)!=a[i]){
            int ans,l=i+1,r=n-1;
            while(l<=r){
                int mid=(l+r)/2;
                int v=get(i,mid);
                if(v>a[i]){
                    ans=mid;
                    r=mid-1;
                }
                else{
                    l=mid+1;
                }
            }
            g[a[i]].push_back(a[ans]);
        }
        if(i!=0&&get(0,i)!=a[i]){
            int ans,l=0,r=i-1;
            while(l<=r){
                int mid=(l+r)/2;
                int v=get(mid,i);
                if(v>a[i]){
                    ans=mid;
                    l=mid+1;
                }
                else{
                    r=mid-1;
                }
            }
            g[a[i]].push_back(a[ans]);
        }
        sort(g[a[i]].begin(),g[a[i]].end());
        if(g[a[i]].size()>0){
            st[a[i]][0][0]=g[a[i]][0];
        }
        else{
            st[a[i]][0][0]=n+1;
        }
        if(g[a[i]].size()>1){
            st[a[i]][0][1]=g[a[i]][1];
        }
        else{
            st[a[i]][0][1]=n+1;
        }
    }
    for(int j=1;j<L;j++){
        for(int i=1;i<=n;i++){
            int r=i;
            r=st[r][j-1][0];
            r=st[r][j-1][0];
            st[i][j][0]=r;
            r=i;
            r=st[r][j-1][1];
            r=st[r][j-1][1];
            st[i][j][1]=r;
        }
    }
}
int dfs(int u,int tar)
{
    int ret=0;
    for(int i=1;i>=0;i--){
        for(int j=L-1;j>=0;j--){
            int r=st[u][j][i];
            if(r<=tar){
                ret+=(1<<j);
                u=r;
            }
        }
    }
    if(u==tar)return ret;
    else return INF;
}
int minimum_jumps(int A,int B,int C,int D){
    int u=a[B];
    int tar=a[C];
    if(u>tar)return -1;
    int l=A,r=B;
    while(l<=r){
        int mid=(l+r)/2;
        if(get(mid,B)<tar){
            r=mid-1;
            u=get(mid,B);
        }
        else{
            l=mid+1;
        }
    }
    int ans=dfs(u,tar);
    if(ans==INF)ans=-1;
    return ans;
}

Compilation message (stderr)

jumps.cpp: In function 'void init(int, std::vector<int>)':
jumps.cpp:51:17: warning: 'ans' may be used uninitialized in this function [-Wmaybe-uninitialized]
   51 |             int ans,l=i+1,r=n-1;
      |                 ^~~

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