[2019.11.28] learning algorithm records - access to all points of the minimum time

You can move in the plane according to the following rules:

Each second horizontal or vertical direction along a unit length, or across the diagonal (each mobile may be regarded as a unit length in the horizontal and vertical directions within one second).
You must appear in the order of the array to access these points.

Example 1:

Input: points = [[1,1], [3,4], [- 1,0]]
Output: 7
Explanation: an optimum access path is: [1,1] -> [2,2] - > [3,3] -> [3,4] -> [2,3] -> [1,2] -> [0,1] -> [1,0]
from [1,1] to [ 3,4] 3 seconds
from [3,4] to [1,0] requires four seconds
requires a total of seven seconds
example 2:

Input: points = [[3,2], [- 2,2]]
Output: 5

prompt:

1. points.length == n
2. 1 <= n <= 100
3. points[i].length == 2
4. -1000 <= points[i][0], points[i][1] <= 1000

Source: stay button (LeetCode)

class Solution {
    public int minTimeToVisitAllPoints(int[][] points) {
        int sum = 0;
        for (int i = 0; i < points.length-1; i++) {
            sum += Math.max(Math.abs(points[i][0] - points[i + 1][0]), Math.abs(points[i][1] - points[i + 1][1]));
        }
        return sum;
    }
}

Ideas
After comparison, the x is actually a comparison between the two points from a large distance y is large, whichever is greater distance between two points that count.

notes

1. Absolute value method:

int number = -2;
int absNumber = Math.abs(number);

2. Take the maximum of two numbers:

int a = 3;
int b = 4;
Math.max(a,b); //输出4

3. onTwo-dimensional arrayusage:

Two-dimensional array can be understood as: an array each element of an array.

• example 1：

int[][] arr = new int[a][b];

a two-dimensional array that represents the number of arrays;
B represents the number of elements of each one-dimensional array.

int[][] arr = new int[2][3];

This two-dimensional array has a two dimensional array, it is expressed as: arr [0], arr [ 1];
for each one-dimensional array with 3 elements, each element was written to call: arr [a] [b] , a represents the first of several array, b represents a bit.

• example 2：

int[][] arr = new int[a][];

a two-dimensional array represents the number of arrays, but the number of elements is not given a one-dimensional array, the number of which can be given dynamically.

int[][] arr = new int[2][];
arr[0] = new int[3];
arr[1] = new int[1];

• example 3：

int[][] arr = {{1，2}，{3，4，5，6}，{7，8，9}}；

Directly to the two-dimensional array are given in the declaration.