This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include <bits/stdc++.h>
#pragma GCC optimize(o3)
#pragma pack(push, 1)
struct QEntry
{
uint16_t building;
uint16_t dogeAndL;
int cost;
QEntry(uint16_t building, uint16_t doge, int cost, bool left)
{
this->building = building;
this->cost = cost;
this->dogeAndL = (doge << 1) | (left ? 1 : 0);
}
bool left()
{
return dogeAndL & 0x1;
}
uint16_t doge()
{
return dogeAndL >> 1;
}
};
#pragma pack(pop)
std::bitset<30000> visited[30000];
int main()
{
int numBuildings, numDoges;
std::cin >> numBuildings;
std::cin >> numDoges;
std::vector<std::vector<int>> dogesInBuildings(numBuildings);
for (int i = 0; i < numBuildings; i++)
dogesInBuildings[i].reserve(numDoges);
std::vector<int> dogePositions(numDoges);
std::vector<int> dogePowers(numDoges);
for (int i = 0; i < numDoges; i++)
{
std::cin >> dogePositions[i];
std::cin >> dogePowers[i];
if (i != 0 && (i == 1 || dogePositions[i] - dogePowers[i] >= 0 || dogePositions[i] + dogePowers[i] < numBuildings))
dogesInBuildings[dogePositions[i]].push_back(i);
}
std::queue<QEntry> q;
q.push(QEntry { dogePositions[0], 0, 0, true });
q.push(QEntry { dogePositions[0], 0, 0, false });
auto MaybePush = [&] (int b, int d, int c, bool l)
{
if (!visited[b][d])
{
visited[b][d] = true;
q.push(QEntry { b, d, c, l });
}
};
while (!q.empty())
{
QEntry entry = q.front();
q.pop();
if (entry.doge() == 1 || dogePositions[1] == entry.building)
{
std::cout << entry.cost << std::endl;
return 0;
}
for (int nextDoge : dogesInBuildings[entry.building])
{
int pBuilding = (int)entry.building - dogePowers[nextDoge];
if (pBuilding >= 0)
MaybePush(pBuilding, nextDoge, entry.cost + 1, true);
int nBuilding = (int)entry.building + dogePowers[nextDoge];
if (nBuilding < numBuildings)
MaybePush(nBuilding, nextDoge, entry.cost + 1, false);
}
dogesInBuildings[entry.building].clear();
if (entry.left())
{
int pBuilding = (int)entry.building - dogePowers[entry.doge()];
if (pBuilding >= 0)
{
MaybePush(pBuilding, entry.doge(), entry.cost + 1, true);
}
}
else
{
int nBuilding = (int)entry.building + dogePowers[entry.doge()];
if (nBuilding < numBuildings)
{
MaybePush(nBuilding, entry.doge(), entry.cost + 1, false);
}
}
}
std::cout << "-1" << std::endl;
}
Compilation message (stderr)
skyscraper.cpp:3:22: warning: '#pragma GCC optimize' is not a string or number [-Wpragmas]
#pragma GCC optimize(o3)
^~
skyscraper.cpp: In function 'int main()':
skyscraper.cpp:56:47: warning: narrowing conversion of 'dogePositions.std::vector<int>::operator[](0)' from '__gnu_cxx::__alloc_traits<std::allocator<int> >::value_type {aka int}' to 'uint16_t {aka short unsigned int}' inside { } [-Wnarrowing]
q.push(QEntry { dogePositions[0], 0, 0, true });
^
skyscraper.cpp:57:48: warning: narrowing conversion of 'dogePositions.std::vector<int>::operator[](0)' from '__gnu_cxx::__alloc_traits<std::allocator<int> >::value_type {aka int}' to 'uint16_t {aka short unsigned int}' inside { } [-Wnarrowing]
q.push(QEntry { dogePositions[0], 0, 0, false });
^
skyscraper.cpp: In lambda function:
skyscraper.cpp:64:31: warning: narrowing conversion of 'b' from 'int' to 'uint16_t {aka short unsigned int}' inside { } [-Wnarrowing]
q.push(QEntry { b, d, c, l });
^
skyscraper.cpp:64:31: warning: narrowing conversion of 'd' from 'int' to 'uint16_t {aka short unsigned int}' inside { } [-Wnarrowing]
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