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Formatted question description: https://leetcode.ca/all/1232.html

# 1232. Check If It Is a Straight Line (Easy)

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.

Related Topics:
Array, Math, Geometry

## Solution 1.

• class Solution {
public boolean checkStraightLine(int[][] coordinates) {
int length = coordinates.length;
if (length == 2)
return true;
int deltaX = coordinates[1][0] - coordinates[0][0], deltaY = coordinates[1][1] - coordinates[0][1];
for (int i = 2; i < length; i++) {
int curDeltaX = coordinates[i][0] - coordinates[i - 1][0], curDeltaY = coordinates[i][1] - coordinates[i - 1][1];
if (deltaX * curDeltaY != deltaY * curDeltaX)
return false;
}
return true;
}
}

############

class Solution {
public boolean checkStraightLine(int[][] coordinates) {
int x1 = coordinates[0][0], y1 = coordinates[0][1];
int x2 = coordinates[1][0], y2 = coordinates[1][1];
for (int i = 2; i < coordinates.length; ++i) {
int x = coordinates[i][0], y = coordinates[i][1];
if ((x - x1) * (y2 - y1) != (y - y1) * (x2 - x1)) {
return false;
}
}
return true;
}
}

• // OJ: https://leetcode.com/problems/check-if-it-is-a-straight-line/
// Time: O(N)
// Space: O(1)
class Solution {
public:
bool checkStraightLine(vector<vector<int>>& A) {
int N = A.size(), x1 = A[0][0], y1 = A[0][1], x2 = A[1][0], y2 = A[1][1];
for (int i = 2; i < N; ++i) {
if ((A[i][1] - y1) * (x2 - x1) != (y2 - y1) * (A[i][0] - x1)) return false;
}
return true;
}
};

• class Solution:
def checkStraightLine(self, coordinates: List[List[int]]) -> bool:
x1, y1 = coordinates[0]
x2, y2 = coordinates[1]
for x, y in coordinates[2:]:
if (x - x1) * (y2 - y1) != (y - y1) * (x2 - x1):
return False
return True

############

# 1232. Check If It Is a Straight Line
# https://leetcode.com/problems/check-if-it-is-a-straight-line/

class Solution:
def checkStraightLine(self, coordinates: List[List[int]]):
(x0,y0), (x1,y1) = coordinates[:2]

return all((x1-x0) * (y-y1) == (x-x1) * (y1-y0) for x,y in coordinates)

• func checkStraightLine(coordinates [][]int) bool {
x1, y1 := coordinates[0][0], coordinates[0][1]
x2, y2 := coordinates[1][0], coordinates[1][1]
for i := 2; i < len(coordinates); i++ {
x, y := coordinates[i][0], coordinates[i][1]
if (x-x1)*(y2-y1) != (y-y1)*(x2-x1) {
return false
}
}
return true
}