#AT2071. C - Knight Fork
C - Knight Fork
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C - Knight Fork
Score : $300$ points
Problem Statement
On an $xy$-coordinate plane, is there a lattice point whose distances from two lattice points $(x_1, y_1)$ and $(x_2, y_2)$ are both $\sqrt{5}$?
Notes
A point on an $xy$-coordinate plane whose $x$ and $y$ coordinates are both integers is called a lattice point.
The distance between two points $(a, b)$ and $(c, d)$ is defined to be the Euclidean distance between them, $\sqrt{(a - c)^2 + (b-d)^2}$.
The following figure illustrates an $xy$-plane with a black circle at $(0, 0)$ and white circles at the lattice points whose distances from $(0, 0)$ are $\sqrt{5}$. (The grid shows where either $x$ or $y$ is an integer.)
Constraints
- $-10^9 \leq x_1 \leq 10^9$
- $-10^9 \leq y_1 \leq 10^9$
- $-10^9 \leq x_2 \leq 10^9$
- $-10^9 \leq y_2 \leq 10^9$
- $(x_1, y_1) \neq (x_2, y_2)$
- All values in input are integers.
Input
Input is given from Standard Input in the following format:
Output
If there is a lattice point satisfying the condition, print Yes
; otherwise, print No
.
0 0 3 3
Yes
- The distance between points $(2,1)$ and $(x_1, y_1)$ is $\sqrt{(0-2)^2 + (0-1)^2} = \sqrt{5}$;
- the distance between points $(2,1)$ and $(x_2, y_2)$ is $\sqrt{(3-2)^2 + (3-1)^2} = \sqrt{5}$;
- point $(2, 1)$ is a lattice point,
so point $(2, 1)$ satisfies the condition. Thus, Yes
should be printed.
One can also assert in the same way that $(1, 2)$ also satisfies the condition.
0 1 2 3
No
No lattice point satisfies the condition, so No
should be printed.
1000000000 1000000000 999999999 999999999
Yes
Point $(10^9 + 1, 10^9 - 2)$ and point $(10^9 - 2, 10^9 + 1)$ satisfy the condition.