Арсений Ефремов

let input = [ a1, a2, ... , aN ] // ordered ascending, N > 1
let k, P // assume k > 0, 1-based indexing
// remove at k, 0-based indexing
for (let i = k; i < N; ++i)
   input[i - 1] = input[i]
// insert P preserving order
for (let i = N - 1; i >= 0; --i) {
   if (i == 0 || P >= input[i - 1]) {
      for (let j = N - 1; j > i; --j)
         input[j] = input[j-1]
      input[i] = P
      break
   } else continue
}
// finish
print(input)

(I)nput := [x0, y0, x1, y1, x2, y2 ... xn, yn]

(R)ational := (a, b)
Trunc(R) := R(a / НОД(a,b), b / НОД(a,b))
R1 + R2 := Trunc(a1*b2 + a2*b1, b1*b2)
R1 + R2 + R3 := (R1 + R2) + R3

Output := R(I[0],I[1]) + R(I[2],I[3]) + ... + R(I[2n-1],I[2n])