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 10000const 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 0xfffffconst 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][n]);    }}