#include <bits/stdc++.h>
#pragma GCC optimize("O3")
#define FOR(i, x, y) for (int i = x; i < y; i++)
typedef long long ll;
using namespace std;
struct Doge {
int jumps, pos, size, direction;
};
vector<pair<int, int>> sky[300001];
bool visited[300001];
int main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
fill(visited, visited + 300001, false);
int n, m;
cin >> n >> m;
int size, pos;
FOR(i, 0, m) {
int a, b;
cin >> a >> b;
sky[a].push_back({i, b});
if (i == 0) size = b, pos = a;
}
queue<Doge> q;
q.push({0, pos, size, 1});
while (!q.empty()) {
Doge curr = q.front();
q.pop();
bool push = true;
// cout << curr.jumps << ' ' << curr.pos << ' ' << curr.size << ' ' << curr.direction << '\n';
if (curr.direction) {
if (curr.pos + curr.size < n) {
if (!visited[curr.pos + curr.size]) {
visited[curr.pos + curr.size] = true;
for (auto& i : sky[curr.pos + curr.size]) {
if (i.first == 1) return cout << curr.jumps + 1 << '\n', 0;
if (i.second != curr.size) {
q.push({curr.jumps + 1, curr.pos + curr.size, i.second, 1});
q.push({curr.jumps + 1, curr.pos + curr.size, i.second, 0});
}
}
} else {
for (auto& i : sky[curr.pos + curr.size]) {
if (i.second == curr.size) {
push = false;
}
}
}
}
if (push && curr.pos + curr.size < n) q.push({curr.jumps + 1, curr.pos + curr.size, curr.size, 1});
} else {
if (curr.pos - curr.size > -1) {
if (!visited[curr.pos - curr.size]) {
visited[curr.pos - curr.size] = true;
for (auto& i : sky[curr.pos - curr.size]) {
if (i.first == 1) return cout << curr.jumps + 1 << '\n', 0;
if (i.second != curr.size) {
q.push({curr.jumps + 1, curr.pos - curr.size, i.second, 1});
q.push({curr.jumps + 1, curr.pos - curr.size, i.second, 0});
}
}
} else {
for (auto& i : sky[curr.pos - curr.size]) {
if (i.second == curr.size) {
push = false;
}
}
}
}
if (push && curr.pos - curr.size > -1) q.push({curr.jumps + 1, curr.pos - curr.size, curr.size, 0});
}
}
cout << "-1\n";
return 0;
}
Compilation message
skyscraper.cpp: In function 'int main()':
skyscraper.cpp:29:11: warning: 'pos' may be used uninitialized in this function [-Wmaybe-uninitialized]
q.push({0, pos, size, 1});
~~~~~~^~~~~~~~~~~~~~~~~~~
skyscraper.cpp:29:11: warning: 'size' may be used uninitialized in this function [-Wmaybe-uninitialized]
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
8 ms |
7680 KB |
Output is correct |
2 |
Incorrect |
7 ms |
7680 KB |
Output isn't correct |
3 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
7 ms |
7680 KB |
Output is correct |
2 |
Incorrect |
7 ms |
7680 KB |
Output isn't correct |
3 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
8 ms |
7680 KB |
Output is correct |
2 |
Incorrect |
8 ms |
7808 KB |
Output isn't correct |
3 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
7 ms |
7680 KB |
Output is correct |
2 |
Incorrect |
8 ms |
7680 KB |
Output isn't correct |
3 |
Halted |
0 ms |
0 KB |
- |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
8 ms |
7680 KB |
Output is correct |
2 |
Incorrect |
8 ms |
7760 KB |
Output isn't correct |
3 |
Halted |
0 ms |
0 KB |
- |