ACQUIRE - Land Acquisition

                           GOLD PROBLEMS
                  Three problems numbered 1 through 3

Problem 1: Land Acquisition [Paul Christiano, 2007]

Farmer John is considering buying more land for the farm and has
his eye on N (1 <= N <= 50,000) additional rectangular plots, each
with integer dimensions (1 <= width_i <= 1,000,000; 1 <= length_i
<= 1,000,000).

If FJ wants to buy a single piece of land, the cost is $1/square
unit, but savings are available for large purchases. He can buy
any number of plots of land for a price in dollars that is the width
of the widest plot times the length of the longest plot. Of course,
land plots cannot be rotated, i.e., if Farmer John buys a 3x5 plot
and a 5x3 plot in a group, he will pay 5x5=25.

FJ wants to grow his farm as much as possible and desires all the
plots of land. Being both clever and frugal, it dawns on him that
he can purchase the land in successive groups, cleverly minimizing
the total cost by grouping various plots that have advantageous
width or length values.

Given the number of plots for sale and the dimensions of each,
determine the minimum amount for which Farmer John can purchase all



* Line 1: A single integer: N

* Lines 2..N+1: Line i+1 describes plot i with two space-separated
        integers: width_i and length_i


100 1
15 15
20 5
1 100


There are four plots for sale with dimensions as shown.


* Line 1: The minimum amount necessary to buy all the plots.




The first group contains a 100x1 plot and costs 100. The next group
contains a 1x100 plot and costs 100. The last group contains both the 20x5
plot and the 15x15 plot and costs 300. The total cost is 500, which is

hide comments
mbfibat: 2018-09-11 16:19:29

AC in 1 go, test cases are correct. Check your code again and again until you find the bug.

kaneki0530: 2018-06-03 13:14:31

WA!!! I followed the method given on Wiki, convex-hull-trick dp solution

totallynotan: 2018-04-11 19:40:03

OK friends if you are getting WA these are the test cases: Hope that helps

basilisk1995: 2018-03-07 14:55:47

I submitted the solution given in the wcipeg article and got WA.

enzymii: 2018-02-03 01:45:00

Good convex hull trick!

narutoumania: 2017-07-30 21:29:22

Finally accepted!!o(n2) solution.useful link for solving

srinu_73: 2017-06-21 10:44:47

Removed irrelevant rectangles and O(n^2) DP passed.

orion_pax: 2017-06-08 06:50:38

I tried both dp and convex hull technique, only latter gives AC (dp solution passes all test cases of spoj toolkit), dp solution gives WA.

jedigeki: 2016-09-15 13:12:24

I haven't read convex hull trick and am trying to pass a O(n^2) solution, but am getting WA.
My code gives the correct answer for all test cases on Kindly help me with a few peculiar test cases.

sieunhanbom04: 2016-08-02 11:18:31

will O(n^2) DP be good enough?
RE: Nice! Convex hull trick...

Last edit: 2016-08-02 16:12:31

Added by:Hasan Jaddouh
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