村镇修电路(ACM).doc

Build The Electric SystemTime Limit: 1 Second Memory Limit: 32768 KB In last winter, there was a big snow storm in South China. The electric system was damaged seriously. Lots of power lines were broken and lots of villages lost contact with the main power grid. The government wants to reconstruct the electric system as soon as possible. So, as a professional programmer, you are asked to write a program to calculate the minimum cost to reconstruct the power lines to make sure theres at least one way between every two villages. InputStandard input will contain multiple test cases. The first line of the input is a single integer T (1 = T = 50) which is the number of test cases. And it will be followed by T consecutive test cases. In each test case, the first line contains two positive integers N and E (2 = N = 500, N = E = N * (N - 1) / 2), representing the number of the villages and the number of the original power lines between villages. There follow E lines, and each of them contains three integers, A, B, K (0 = A, B N, 0 = K 1000). A and B respectively means the index of the starting village and ending village of the power line. If K is 0, it means this line still works fine after the snow storm. If K is a positive integer, it means this line will cost K to reconstruct. There will be at most one line between any two villages, and there will not be any line from one village to itself. OutputFor each test case in the input, theres only one line that contains the minimum cost to recover the electric system to make sure that theres at least one way between every two villages. Sample Input13 30 1 50 2 01 2 9Sample Output5#include /直接bfs无向图mstint a125000,b125000,k125000;int village501; /村庄的出现与否 -1 or 0void pai_xu(int e) /k 递增 int i,j,temp; for(i=0;ie-1;i+) for(j=i+1;jkj) temp=ki;ki=kj;kj=temp; temp=ai;ai=aj;aj=temp; temp=bi;bi=bj;bj=temp; int main() int i,t,j,h,sum,n,e; while(scanf(%d,&t)!=EOF) for(i=0;it;i+) scanf(%d%d,&n,&e); for(j=0;je;j+) scanf(%d%d%d,&aj,&bj,&kj); for(j=0;jn;j+) villagej=0; pai_xu(e); villagea0=villageb0=-1; sum=k0; for(j=1;jn;j+) for(h=1;he;h+) if(villageah!=-1&vil