Re: [閒聊] 每日LeetCode

[Che31128 (飛天浣熊)]

https://leetcode.com/problems/check-if-it-is-a-straight-line/description/
1232. Check If It Is a Straight Line
給一個陣列coordinates[i][j]，coordinates[i]為第i+1個點，j=0為x軸
j=1為y軸，判斷這幾個點是否連成一線。

Example 1:
https://assets.leetcode.com/uploads/2019/10/15/untitled-diagram-2.jpg
Input: coordinates = [[1,2],[2,3],[3,4],[4,5],[5,6],[6,7]]
Output: true

Example 2:
https://assets.leetcode.com/uploads/2019/10/09/untitled-diagram-1.jpg
Input: coordinates = [[1,1],[2,2],[3,4],[4,5],[5,6],[7,7]]
Output: false

思路：
1.找出第一個點與第二點的斜率，依序尋找每一點斜率是否相等。
2.為防止runtime error用乘法來判斷。

java code
--------------------------------------------------------------------------
class Solution {
    public boolean checkStraightLine(int[][] coordinates) {

       int moveX = coordinates[1][0]-coordinates[0][0];
       int moveY = coordinates[1][1]-coordinates[0][1];

        for(int i = 2 ; i < coordinates.length ; i++){

            int moveX1 = coordinates[i][0]-coordinates[i-1][0];
            int moveY1 = coordinates[i][1]-coordinates[i-1][1];

            if((moveY*moveX1) ! = (moveY1*moveX))
            return false;
        }
        return true;
    }
}
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姆咪只能寫easy題:((((

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