feat(src): add 54-spiralOrder

Author: kwu130

src/54-spiralOrder.cpp

@@ -0,0 +1,75 @@
+//
+// Created by 1412 on 2025/10/31.
+//
+
+#include <bits/stdc++.h>
+
+using namespace std;
+
+class Solution {
+public:
+    vector<int> spiralOrder(vector<vector<int>>& matrix) {
+        int m = matrix.size();
+        int n = matrix[0].size();
+        vector<int> res;
+        res.reserve(m * n);
+        int i = 0, j = 0;
+        while (res.size() < m * n) {
+            while (i >= 0 && i < m && j >= 0 && j < n && matrix[i][j] != INT_MIN) {
+                res.push_back(matrix[i][j]);
+                matrix[i][j] = INT_MIN;
+                j++;
+            }
+            j--;
+            i++;
+            while (i >= 0 && i < m && j >= 0 && j < n && matrix[i][j] != INT_MIN) {
+                res.push_back(matrix[i][j]);
+                matrix[i][j] = INT_MIN;
+                i++;
+            }
+            i--;
+            j--;
+            while (i >= 0 && i < m && j >= 0 && j < n && matrix[i][j] != INT_MIN) {
+                res.push_back(matrix[i][j]);
+                matrix[i][j] = INT_MIN;
+                j--;
+            }
+            j++;
+            i--;
+            while (i >= 0 && i < m && j >= 0 && j < n && matrix[i][j] != INT_MIN) {
+                res.push_back(matrix[i][j]);
+                matrix[i][j] = INT_MIN;
+                i--;
+            }
+            i++;
+            j++;
+        }
+        return res;
+    }
+};
+
+void test() {
+    Solution s;
+    vector<vector<int>> matrix = {
+        {1, 2, 3},
+        {4, 5, 6},
+        {7, 8, 9}
+    };
+    vector<int> expected = {1, 2, 3, 6, 9, 8, 7, 4, 5};
+    vector<int> res = s.spiralOrder(matrix);
+    assert(res == expected);
+
+    matrix = {
+        {1,  2,  3,  4},
+        {5,  6,  7,  8},
+        {9, 10, 11, 12}
+    };
+    expected = {1, 2, 3, 4, 8, 12, 11, 10, 9, 5, 6, 7};
+    res = s.spiralOrder(matrix);
+    assert(res == expected);
+}
+
+int main() {
+    test();
+    return 0;
+}