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LeetCode/cpp/spiral-matrix.cpp
Matej Focko b229608723
cpp(chore): add clang-format style and format
Signed-off-by: Matej Focko <me@mfocko.xyz>
2024-01-03 12:06:54 +01:00

91 lines
2.4 KiB
C++

#include <cassert>
#include <vector>
class Solution {
struct indices {
int x;
int y;
bool operator==(const indices &other) const = default;
indices &operator+=(const indices &other) {
x += other.x;
y += other.y;
return *this;
}
friend indices operator+(indices left, const indices &right) {
return left += right;
}
int operator[](const std::vector<std::vector<int>> &mat) const {
return mat[y][x];
}
};
struct spiral_indices {
spiral_indices(const std::vector<std::vector<int>> &matrix)
: x_bounds{-1, static_cast<int>(matrix[0].size())},
y_bounds{-1, static_cast<int>(matrix.size())} {}
bool done() const { return !in_bounds(idx); }
spiral_indices &operator++() {
// update bounds and change the direction if cannot move
if (!in_bounds(idx + d)) {
// change the direction
d = {-d.y, d.x};
// get the magnitude of the vector
auto flat_d = d.x + d.y;
// decide whether we're moving x or y bounds
auto &bounds = d.x ? x_bounds : y_bounds;
if (flat_d > 0) {
bounds.x++;
} else {
bounds.y--;
}
}
idx += d;
return *this;
}
int operator[](const std::vector<std::vector<int>> &mat) const {
return idx[mat];
}
private:
indices idx{0, 0};
indices d{1, 0};
indices x_bounds, y_bounds;
bool in_bounds(const indices &idx) const {
return (x_bounds.x < idx.x && idx.x < x_bounds.y) &&
(y_bounds.x < idx.y && idx.y < y_bounds.y);
}
};
public:
std::vector<int> spiralOrder(const std::vector<std::vector<int>> &matrix) {
std::vector<int> spiral;
for (spiral_indices idx{matrix}; !idx.done(); ++idx) {
spiral.push_back(idx[matrix]);
}
return spiral;
}
};
int main() {
Solution s;
assert((s.spiralOrder({{1, 2, 3}, {4, 5, 6}, {7, 8, 9}}) ==
std::vector{1, 2, 3, 6, 9, 8, 7, 4, 5}));
assert((s.spiralOrder({{1, 2, 3, 4}, {5, 6, 7, 8}, {9, 10, 11, 12}}) ==
std::vector{1, 2, 3, 4, 8, 12, 11, 10, 9, 5, 6, 7}));
return 0;
}