HDU 1874 畅通工程续 + HDU 2544 最短路 最短路水题，floyd水

题目：

1874 http://acm.hdu.edu.cn/showproblem.php?pid=1874

2444 http://acm.hdu.edu.cn/showproblem.php?pid=2544

裸单源最短路径。。。水题。。。

用很水的方法，floyd水果，复杂度n^3很吓人啊。。。。慢慢学各种最短路算法，这几题都要再用各种方法水一遍。。。

最近考试，伤不起呢。。。

1874：

#include <cstdio>
#include <cstring>
using namespace std;
#define INF 10000
const int maxn = 201;
int r[maxn][maxn];

int main() {
int n, m;
while (scanf("%d%d", &n, &m) != EOF) {
memset (r, INF, sizeof(r));
int x, y, v;
for (int i = 0; i < m; i++) {
scanf("%d%d%d", &x, &y, &v);
if (r[x][y] > v)
r[x][y] = r[y][x] = v;
}//for
for (int i = 0; i < n ;i++)
r[i][i] = 0;
for (int k = 0; k < n; k++)
for (int i = 0; i < n; i++)
for (int j = 0; j < n; j++) {
if (r[i][k] + r[k][j] < r[i][j])
r[i][j] = r[j][i] = r[i][k] + r[k][j];
}//for
scanf("%d%d", &x, &y);
if (r[x][y] < INF)
printf("%d\n", r[x][y]);
else
printf("-1\n");
}//while
return 0;
}//hehe

2444

#include <cstdio>
#include <cstring>
#define INF 0xfffff
const int maxn = 1002;
int p[maxn][maxn];

int main() {
int n, m;
int i, j, k;
//    freopen("in", "r", stdin);
while (scanf("%d%d", &n, &m) && n && m) {
for (i = 1; i <= n; i++)
for (j = 1; j <= n; j++)
if (j == i)
p[i][j] = p[j][i] = 0;
else
p[i][j] = p[j][i] = INF;
int x, y, w;
for (i = 0; i < m; i++) {
scanf("%d%d%d", &x, &y, &w);
if (p[x][y] > w)
p[x][y] = p[y][x] = w;
}
for (i = 1; i <= n; i++)
for (j = 1; j <= n; j++)
for (k = 1; k <= n; k++)
if (p[i][k] + p[k][j] < p[i][j])
p[i][j] = p[j][i] = p[i][k] + p[k][j];
printf("%d\n", p[1]
);
}
}