Submission #739458

#	Time	Username	Problem	Language	Result	Execution time	Memory
739458		Username4132	Jakarta Skyscrapers (APIO15_skyscraper)	C++14	100 / 100	251 ms	12424 KiB

skyscraper

#include<iostream>
#include<vector>
#include<queue>
#include<set>
using namespace std;
#define forn(i, n) for(int i=0; i<(int)n; ++i)
#define PB push_back

struct node{
    int pos, hop, cost;
    bool le, ri;
    node(int Pos, int Hop, int Cost, bool Le=true, bool Ri=true) : pos(Pos), hop(Hop), cost(Cost), le(Le), ri(Ri) {}
};

const int MAXN=30010, SQ=180;
int n, m, sq, start, target;
bool done[MAXN];
vector<int> ops[MAXN];
bool len[2][MAXN][SQ];
deque<node> Q;

void add(node v, bool mode){
    if(v.hop>=sq || !len[mode][v.pos][v.hop]){
        if(v.hop<sq) len[mode][v.pos][v.hop]=true;
        if(mode) Q.push_back(v);
        else Q.push_front(v);
    }
}

int main(){
    scanf("%d %d", &n, &m);
    while((sq+1)*(sq+1)<=n) ++sq;
    forn(i, m){
        int a, b; scanf("%d %d", &a, &b);
        ops[a].PB(b);
        if(i==0) start=a;
        if(i==1) target=a;
    }
    for(int doge:ops[start]) add(node(start, doge, 0), false);
    int ans=-1;
    while(!Q.empty()){
        node v = Q.front();
        Q.pop_front();
        if(v.pos==target){
            ans=v.cost;
            break;
        }
        int le=v.pos-v.hop, ri=v.pos+v.hop;
        if(le>=0 && v.le) add(node(le, v.hop, v.cost+1, true, false), true);
        if(ri<n && v.ri) add(node(ri, v.hop, v.cost+1, false, true), true);
        if(!done[v.pos]){
            for(int wi:ops[v.pos]) add(node(v.pos, wi, v.cost), false);
            done[v.pos]=true;
        }
    }
    printf("%d\n", ans);
}

Compilation message (stderr)

skyscraper.cpp: In function 'int main()':
skyscraper.cpp:31:10: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   31 |     scanf("%d %d", &n, &m);
      |     ~~~~~^~~~~~~~~~~~~~~~~
skyscraper.cpp:34:24: warning: ignoring return value of 'int scanf(const char*, ...)' declared with attribute 'warn_unused_result' [-Wunused-result]
   34 |         int a, b; scanf("%d %d", &a, &b);
      |                   ~~~~~^~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 12 / 12
• Subtask 3: 14 / 14
• Subtask 4: 21 / 21
• Subtask 5: 43 / 43