poj 2485 Highways
2012-03-18 13:42
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今天在做图论的题目。感觉图论的题目要不就不会做,要会做比较容易1a,因为坑人的地方比较少。
/*
POJ: 2485 Highways
*/
#include <iostream>
#include <cstdio>
#include <cstring>
#define MaxV 505
#define MaxL (1 << 20)
using namespace std;
long length[MaxV][MaxV];
int n;
int dis[MaxV];
bool used[MaxV];
long Prim();
int main()
{
int t;
//freopen("data.in", "rb", stdin);
scanf("%d", &t);
while(t--) {
scanf("%d", &n);
for(int i = 0; i < n; i++) {
for(int j = 0; j < n; j++) {
scanf("%d", &length[i][j]);
}
}
printf("%ld\n", Prim());
}
return 0;
}
long Prim()
{
long max_length = -1;
for(int i = 1; i < n; i++) {
used[i] = false;
}
used[0] = true;
dis[0] = 0;
for(int i = 1; i < n; i++) {
dis[i] = length[0][i];
}
for(int i = 0; i < n - 1; i++) {
long tmp = MaxL;
int tmp_index = 0;
for(int j = 0; j < n; j++) {
if(!used[j] && dis[j] < tmp) {
tmp = dis[j];
tmp_index = j;
}
}
used[tmp_index] = true;
max_length = max_length > tmp ? max_length : tmp;
for(int k = 0; k < n; k++) {
if(!used[k] && dis[k] > length[tmp_index][k]) {
dis[k] = length[tmp_index][k];
}
}
}
return max_length;
}
/*
POJ: 2485 Highways
*/
#include <iostream>
#include <cstdio>
#include <cstring>
#define MaxV 505
#define MaxL (1 << 20)
using namespace std;
long length[MaxV][MaxV];
int n;
int dis[MaxV];
bool used[MaxV];
long Prim();
int main()
{
int t;
//freopen("data.in", "rb", stdin);
scanf("%d", &t);
while(t--) {
scanf("%d", &n);
for(int i = 0; i < n; i++) {
for(int j = 0; j < n; j++) {
scanf("%d", &length[i][j]);
}
}
printf("%ld\n", Prim());
}
return 0;
}
long Prim()
{
long max_length = -1;
for(int i = 1; i < n; i++) {
used[i] = false;
}
used[0] = true;
dis[0] = 0;
for(int i = 1; i < n; i++) {
dis[i] = length[0][i];
}
for(int i = 0; i < n - 1; i++) {
long tmp = MaxL;
int tmp_index = 0;
for(int j = 0; j < n; j++) {
if(!used[j] && dis[j] < tmp) {
tmp = dis[j];
tmp_index = j;
}
}
used[tmp_index] = true;
max_length = max_length > tmp ? max_length : tmp;
for(int k = 0; k < n; k++) {
if(!used[k] && dis[k] > length[tmp_index][k]) {
dis[k] = length[tmp_index][k];
}
}
}
return max_length;
}
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