10801 - Lift Hopping

/*10801 - Lift Hopping * 以每一层楼为顶点，每个电梯可以到达的两层楼之间的秒数为每一条边的权值， * 以此构建一个无向图。然后利用dijkstra求出最短的时间， * 注意每次换乘电梯需要等待60s（注意初始定点不需要60s的等待）。*/import java.util.Arrays;import java.util.Scanner;class Main {static final int INF = 100000;static final int MAXN = 105;static final int MAXS = 10;static int[] speed = new int[MAXS];static int[] floors = new int[MAXN];static int[] d = new int[MAXN];static int[][] w = new int[MAXN][MAXN];static int[] vis = new int[MAXN];static int n, k;static int num;public static void main(String[] args) {Scanner scanner = new Scanner(System.in);while (scanner.hasNext()) {String s = scanner.nextLine();String[] ss = s.split(" ");n = Integer.parseInt(ss[0]);k = Integer.parseInt(ss[1]);for (int i = 0; i < MAXN; i++) {Arrays.fill(w[i], INF);}s = scanner.nextLine();ss = s.split(" ");for (int i = 1; i <= n; i++) {speed[i] = Integer.parseInt(ss[i - 1]);}for (int i = 1; i <= n; i++) {num = 0;s = scanner.nextLine();ss = s.split(" ");for (num = 0; num < ss.length; num++)floors[num] = Integer.parseInt(ss[num]);build_graph(i);}if (k == 0) {System.out.println(0);continue;}dijkstra();}}private static void build_graph(int s) {// 构造无向图for (int i = 0; i < num; i++) {for (int j = i + 1; j < num; j++) {int dis = Math.abs(floors[i] - floors[j]) * speed[s];//权值计算if (w[floors[i]][floors[j]] > dis)//更新w[floors[i]][floors[j]] = w[floors[j]][floors[i]] = dis;}}}private static void dijkstra() {Arrays.fill(vis, 0);Arrays.fill(d, INF);d[0] = 0;for (int i = 0; i < MAXN; i++) {int x = 0, m = INF;for (int y = 0; y < MAXN; y++) {// 找到还未标记的节点中d值最小的节点xif (vis[y] == 0 && d[y] <= m)m = d[x = y];}vis[x] = 1;// 标记for (int y = 0; y < MAXN; y++) {// 更新从x出发的所有边d[y] = Math.min(d[y], d[x] + w[x][y] + 60);}}if (d[k] == INF) {System.out.println("IMPOSSIBLE");} else {System.out.println(d[k] - 60);//注意减去60}}}