1232. Check If It Is a Straight Line

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1232. Check If It Is a Straight Line

Description

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

Example 1:

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

Example 2:

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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
  • coordinatescontains no duplicate point.

Hints/Notes

Solution

Language: C++

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class Solution {
public:
    bool checkStraightLine(vector<vector<int>>& coordinates) {
        if (coordinates.size() == 2) {
            return true;
        }
        int dx0 = coordinates[0][0] - coordinates[1][0];
        int dy0 = coordinates[0][1] - coordinates[1][1];
        // dy0 / dx0 = dy / dx => dy0 * dx = dx0 * dy
        int n = coordinates.size();
        for (int i = 2; i < coordinates.size(); i++) {
            int dx = coordinates[i][0] - coordinates[0][0];
            int dy = coordinates[i][1] - coordinates[0][1];
            if (dx * dy0 != dx0 * dy) {
                return false;
            }
        }
        return true;
    }
};