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Create 3531. Count Covered Buildings #955

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Merged
Chayandas07 merged 1 commit into from
Dec 11, 2025
Merged

Create 3531. Count Covered Buildings #955

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36 changes: 36 additions & 0 deletions 3531. Count Covered Buildings
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Original file line number Diff line number Diff line change
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class Solution {
public:
int countCoveredBuildings(int n, vector<vector<int>>& buildings) {
unordered_map<int, set<int>> rowToCol, colToRow;
for (auto &b : buildings) {
int x = b[0], y = b[1];
rowToCol[x].insert(y);
colToRow[y].insert(x);
}

int cnt = 0;
for (auto &b : buildings) {
int x = b[0], y = b[1];
auto &cols = rowToCol[x];
auto it = cols.lower_bound(y);
bool hasLeft = (it != cols.begin());
bool hasRight = false;
if (it != cols.end()) {
auto it2 = it; ++it2;
hasRight = (it2 != cols.end());
}

auto &rows = colToRow[y];
auto it3 = rows.lower_bound(x);
bool hasUp = (it3 != rows.begin());
bool hasDown = false;
if (it3 != rows.end()) {
auto it4 = it3; ++it4;
hasDown = (it4 != rows.end());
}

if (hasLeft && hasRight && hasUp && hasDown) cnt++;
}
return cnt;
}
};
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