Submission #415225

#	Time	Username	Problem	Language	Result	Execution time	Memory
415225		A_D	Rainforest Jumps (APIO21_jumps)	C++14	23 / 100	3342 ms	44108 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];
bool vis[NN];
int seg[4*NN];
int n;
vector<int> g[NN];
vector<int> vec;
int st[NN][L][2];
void build(int p,int s,int e)
{
	if(s==e){
		seg[p]=a[s];
		return;
	}
	int mid=(s+e)/2;
	build(2*p,s,mid);
	build(2*p+1,mid+1,e);
	seg[p]=max( seg[2*p],seg[2*p+1]);
}

int get(int p,int s,int e,int a, int b)
{
    if(a<=s&&e<=b){
		return seg[p];
    }
	if(s>b||e<a){
		return 0;
	}
	int mid=(s+e)/2;
	return max(get(2*p,s,mid,a,b),get(2*p+1,mid+1,e,a,b));
}

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];
    }
    build(1,0,n-1);
    for(int i=0;i<n;i++){
        if(i!=n-1&&get(1,0,n-1,i,n-1)!=a[i]){
            int ans,l=i,r=n-1;
            while(l<=r){
                int mid=(l+r)/2;
                int v=get(1,0,n-1,i+1,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(1,0,n-1,0,i)!=a[i]){
            int ans,l=0,r=i;
            while(l<=r){
                int mid=(l+r)/2;
                int v=get(1,0,n-1,mid,i-1);
                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[A];
    int tar=a[C];
    
    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:52:17: warning: 'ans' may be used uninitialized in this function [-Wmaybe-uninitialized]
   52 |             int ans,l=i,r=n-1;
      |                 ^~~

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