Create check-if-it-is-a-straight-line.cpp

Author: kamyu104

C++/check-if-it-is-a-straight-line.cpp

@@ -0,0 +1,17 @@
+// Time:  O(n)
+// Space: O(1)
+
+class Solution {
+public:
+    bool checkStraightLine(vector<vector<int>>& coordinates) {
+        const auto& i = coordinates[0], &j = coordinates[1];
+        return all_of(coordinates.cbegin() + 2,
+                      coordinates.cend(),
+                      [&](const auto& k) {
+                          return i[0] * j[1] - j[0] * i[1] +
+                                 j[0] * k[1] - k[0] * j[1] +
+                                 k[0] * i[1] - i[0] * k[1] == 0;
+                      }
+               );
+    }
+};