Today I have done leetcode's June LeetCoding Challenge with cpp.

June LeetCoding Challenge 5

Description

Check If It Is a Straight Line

You are given an array coordinates, coordinates[i] = [x, y], where [x, y] represents the coordinate of a point. Check if these points make a straight line in the XY plane.

Example 1:

Input: coordinates = [[1,2],[2,3],[3,4],[4,5],[5,6],[6,7]]
Output: true

Example 2:

Input: coordinates = [[1,1],[2,2],[3,4],[4,5],[5,6],[7,7]]
Output: false

Constraints:

• 2 <= coordinates.length <= 1000
• coordinates[i].length == 2
• -10^4 <= coordinates[i][0], coordinates[i][1] <= 10^4
• coordinates contains no duplicate point.

Solution

class Solution {
public:
  bool checkStraightLine(vector<vector<int>>& coordinates) {
    int dx = coordinates[1][0] - coordinates[0][0];
    int dy = coordinates[1][1] - coordinates[0][1];
    bool result = true;
    for(int i = 2; i < coordinates.size() && result; ++i) {
      int ndx = coordinates[i][0] - coordinates[0][0];
      int ndy = coordinates[i][1] - coordinates[0][1];
      if(dx && ndy * dx != ndx * dy) result = false;
      if(!dx && ndx) result = false;
    }

    return result;
  }
};

// Accepted
// 79/79 cases passed (7 ms)
// Your runtime beats 90.62 % of cpp submissions
// Your memory usage beats 63.27 % of cpp submissions (10 MB)