[BUG] Incorrect coordinate subtraction in DistanceFormula.euclideanDistance #7746

Description

In com.thealgorithms.maths.DistanceFormula.java, the method euclideanDistance(double x1, double y1, double x2, double y2) incorrectly subtracts x1 instead of y1 when computing the y-axis delta:

public static double euclideanDistance(double x1, double y1, double x2, double y2) {
    double dX = Math.pow(x2 - x1, 2);
    double dY = Math.pow(y2 - x1, 2); // <--- Bug: x1 used instead of y1
    return Math.sqrt(dX + dY);
}

As a result, it computes $\sqrt{(x_2 - x_1)^2 + (y_2 - x_1)^2}$ instead of the Euclidean distance $\sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2}$.

In addition, DistanceFormulaTest.java hardcoded incorrect expected values that were produced by the buggy formula (for example, expecting $\sqrt{50} \approx 7.0710678$ instead of the true Euclidean distance $\sqrt{58} \approx 7.6157731$ for points (1, 3) and (8, 0)).

Steps to reproduce

// Calculating Euclidean distance between (1, 3) and (8, 0)
// dx = 8 - 1 = 7, dy = 0 - 3 = -3
// Expected: sqrt(7^2 + (-3)^2) = sqrt(58) ≈ 7.615773105863909
double distance = DistanceFormula.euclideanDistance(1, 3, 8, 0);
System.out.println(distance); // Prints 7.0710678118654755 (which is sqrt(50))

Expected behavior

DistanceFormula.euclideanDistance(x1, y1, x2, y2) should subtract $y_1$ from $y_2$ (Math.pow(y2 - y1, 2)), correctly yielding $\sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2}$.