feat: 59_spiral_matrix_2

59_spiral_matrix_2/main.cpp

@@ -0,0 +1,58 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+class Solution {
+   private:
+    // {row, col}
+    const vector<pair<int, int>> directions{
+        {0, 1},
+        {1, 0},
+        {0, -1},
+        {-1, 0},
+    };
+
+    inline pair<int, int> addPair(const pair<int, int>& x, const pair<int, int>& y) {
+        return {x.first + y.first, x.second + y.second};
+    }
+
+    void nextDirection(int& index, pair<int, int>& direction) {
+        if (++index >= 4) index = 0;
+        direction = directions[index];
+    }
+
+   public:
+    vector<vector<int>> generateMatrix(int n) {
+        vector<vector<int>> matrix(n + 2, vector<int>(n + 2, 0));
+        for (int i = 0; i < n + 2; i++)
+            matrix[i][0] = INT32_MAX,
+            matrix[i][n + 1] = INT32_MAX,
+            matrix[0][i] = INT32_MAX,
+            matrix[n + 1][i] = INT32_MAX;
+
+        int directionIndex = 0;
+        pair<int, int> direction = directions[directionIndex];
+        pair<int, int> currentPos{1, 1};
+
+        for (int i = 1; i <= n * n; i++) {
+            auto nextPos = addPair(currentPos, direction);
+            if (matrix[nextPos.first][nextPos.second] > 0) {
+                nextDirection(directionIndex, direction);
+                nextPos = addPair(currentPos, direction);
+            }
+            matrix[currentPos.first][currentPos.second] = i;
+            currentPos = nextPos;
+        }
+
+        vector<vector<int>> result(n, vector<int>(n, 0));
+        for (int i = 1; i < n + 1; i++)
+            for (int j = 1; j < n + 1; j++)
+                result[i - 1][j - 1] = matrix[i][j];
+
+        return result;
+    }
+};
+
+int main() {
+    Solution().generateMatrix(3);
+    return 0;
+}