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