MMAXPER  Rectangles Perimeter
https://codeforces.com/group/FLVn1Sc504/contest/274506/problem/S
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Given are n rectangles, numbered from 1 to n. We place them tightly on the axis OX, from left to right, according to rectangles' numbers. Each rectangle stays on the axis OX either by its shorter or by its longer side (see the picture below). Compute the length of the upper envelop line, i.e. perimeter's length of the obtained figure minus the length of the left, right and bottom straight line segments of the picture. Write program to find the maximum possible length of the upper envelop line.
Input
On the first line of the standard input, the value of n is written. On each of the next n lines, two integers are given – a_i and b_i – the side lengths of the i_th rectangle.
Constraints: 0 < n < 1000; 0 < a_i < b_i < 1000, for each i = 1, 2, …, n.
Output
On a line of the standard output, your program should write the result as a positive integer.
SAMPLE INPUT: 5 2 5 3 8 1 10 7 14 2 5
SAMPLE OUTPUT: 68
Explanation
A configuration, that yields the maximum length of the upper envelopline, is presented on the picture. The upper envelop line consists of segments DC, CG, GF, FJ, JI, IM, ML, LP, and PO. The total length is 5 + 6 + 3 + 7 + 10 + 13 + 7 + 12 + 5 = 68
Problem for kid  Please, think like kid.
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yash5507:
20201225 19:13:45
AC in 1 go! Used DP with states index and both ways to keep it . Happy Coding :) Last edit: 20201225 19:53:20 

lakshya1st:
20200917 18:07:00
AC in one go:) easy memoization using bottomup DP 

kumar_anubhav:
20200815 11:58:24
@amansahu112 have you solved using dp ? if yes then what states you have assumed to solve the problem ?


amansahu112:
20200501 15:24:23
AC in 1 go 
Added by:  ~!(*(@*!@^& 
Date:  20090217 
Time limit:  1s 
Source limit:  50000B 
Memory limit:  1536MB 
Cluster:  Cube (Intel G860) 
Languages:  All except: ERL JSRHINO NODEJS PERL6 VB.NET 
Resource:  BOI For Kid 08 