#include <stdio.h>
#include <algorithm>
#include <vector>
#include <queue>
using namespace std;
#define all(v) v.begin(), v.end()
#define maxint 2E9
struct Node{
int u;
int dist;
Node (int u_, int d_) {u = u_; dist = d_;}
bool operator < (const Node &a) const {return dist > a.dist;}
};
int N, M;
int B[30001];
int P[30001];
vector<int> V[30000];
int dist[30000];
void get_input(){
scanf("%d%d", &N, &M);
for (int i=0; i<M; i++) {
scanf("%d%d", &B[i], &P[i]);
V[B[i]].push_back(P[i]);
}
for (int i=0; i<N; i++) {
sort(all(V[i]));
V[i].erase(unique(all(V[i])), V[i].end());
}
}
void dijkstra(){
for (int i=0; i<N; i++) {
dist[i] = maxint;
}
int start = B[0];
dist[start] = 0;
priority_queue<Node> Q;
Q.push(Node(start, 0));
while (!Q.empty()){
int u = Q.top().u;
int dist_u= Q.top().dist;
Q.pop();
if (dist_u > dist[u]){
continue;
}
for (int i=0; i < (V[u]).size(); i++){
int power = V[u][i];
int to = u+power;
int cost = dist_u + 1;
while (to < N){
if (dist[to] > cost){
dist[to] = cost;
Q.push(Node(to, cost));
if (binary_search(all(V[to]), power)) break;
}
to += power;
cost += 1;
}
to = u-power;
cost = dist_u + 1;
while (to >= 0){
if (dist[to]>cost){
dist[to]=cost;
Q.push(Node(to, cost));
if (binary_search(all(V[to]), power)) break;
}
to -= power;
cost += 1;
}
}
}
}
int main(){
get_input();
dijkstra();
int ans = dist[B[1]];
if (ans == maxint){
printf("-1\n");
}
else{
printf("%d\n", ans);
}
return 0;
}
Compilation message
File "skyscraper.py", line 5
using namespace std;
^
SyntaxError: invalid syntax
