
ZOJ Problem Set  3204
You have n computers numbered from 1 to n and you want to connect them to make a small local area network (LAN). All connections are twoway (that is connecting computers i and j is the same as connecting computers j and i). The cost of connecting computer i and computer j is c_{ij}. You cannot connect some pairs of computers due to some particular reasons. You want to connect them so that every computer connects to any other one directly or indirectly and you also want to pay as little as possible. Given n and each c_{ij} , find the cheapest way to connect computers.
Input There are multiple test cases. The first line of input contains an integer T (T <= 100), indicating the number of test cases. Then T test cases follow. The first line of each test case contains an integer n (1 < n <= 100). Then n lines follow, each of which contains n integers separated by a space. The jth integer of the ith line in these n lines is c_{ij}, indicating the cost of connecting computers i and j (c_{ij} = 0 means that you cannot connect them). 0 <= c_{ij} <= 60000, c_{ij} = c_{ji}, c_{ii} = 0, 1 <= i, j <= n. Output For each test case, if you can connect the computers together, output the method in in the following fomat: i_{1} j_{1} i_{1} j_{1} ...... where i_{k} i_{k} (k >= 1) are the identification numbers of the two computers to be connected. All the integers must be separated by a space and there must be no extra space at the end of the line. If there are multiple solutions, output the lexicographically smallest one (see hints for the definition of "lexicography small") If you cannot connect them, just output "1" in the line. Sample Input 2 3 0 2 3 2 0 5 3 5 0 2 0 0 0 0 Sample Output 1 2 1 3 1
Hints: Author: CAO, Peng Source: The 6th Zhejiang Provincial Collegiate Programming Contest 