ACPC10D  Tri graphs
Here’s a simple graph problem: Find the shortest path from the topmiddle vertex to the bottommiddle vertex in a given trigraph. A trigraph is an acyclic graph of (N ≥ 2) rows and exactly 3 columns. Unlike regular graphs, the costs in a trigraph are associated with the vertices rather than the edges.
So, considering the example with N = 4, the cost of going straight down from the top to bottom along the middle vertices is 7 + 13 + 3 + 6 = 29. The layout of the directional edges in the graph are always the same as illustrated in the figure.
Input
Your program will be tested on one or more test cases.
Each test case is specified using N + 1 lines where the first line specifies a single integer (2 ≤ N ≤ 100, 000) denoting the number of rows in the graph. N lines follow, each specifying three integers representing the cost of the vertices on the ith row from left to right. The square of each cost value is less than 1,000,000.
The last case is followed by a line with a single zero.
Output
For each test case, print the following line:
k. n
Where k is the test case number (starting at one,) and n is the least cost to go from the topmiddle vertex to the bottommiddle vertex.
Example
Input:
4
13 7 5
7 13 6
14 3 12
15 6 16
0
Output:
1. 22
hide comments
surayans tiwari(http://bit.ly/1EPzcpv):
20160615 11:38:21
test case are good 

kshubham02:
20160607 15:07:54
Easy DP :) 

prateek1985:
20160223 00:04:58
Java users do use fast i/o to get acc!!! 

saini428:
20160122 16:05:27
simple dp


dokz:
20160119 12:19:12
Simple dynamic for O(3 * n), just don't forget that you need to start from the MIDDLE top vertex, and some moves are impossible for the first two rows. 

Utkarsh Agarwal:
20160116 07:23:02
Issue with recursive solution ?? Itterative solution accepted .. Anybody with an accepted recursive soln ? 

Abishek:
20160116 04:17:01
top down gave runtime error . got AC with bottom up . 

karthik1997:
20160102 13:33:15
3 wa because of using fast i/o method for which i realized later that it would not scan negative values.


yashwanth_58:
20151208 14:27:58
Last edit: 20151208 14:44:12 

Akshay Damle:
20151017 17:32:51
1 WA for not considering output format >.< why does this always happen : 
Added by:  Omar ElAzazy 
Date:  20101130 
Time limit:  1s 
Source limit:  50000B 
Memory limit:  1536MB 
Cluster:  Cube (Intel G860) 
Languages:  All except: ASM64 
Resource:  ACPC 2010 