Resource limitation
Time limit: 3.0s Memory limit: 256.0MB
Problem description
Given the length of the one-way edge between two pairs of n nodes, find the shortest path between them.
Input format
The first line of input contains an integer n, representing the number of points.
Next n lines, each line contains n integers, the i-th line represents the length of the side from the i-th point to each point, if there is no side, it is represented by 0.
Output format
Output n lines, the i-th line represents the shortest path length from the i-th point to other points, if there is no reachable path, then output -1.
Sample input
3
0 1 0
0 0 6
0 2 0
sample output
0 1 7
-1 0 6
-1 2 0
data size and convention
1<=n<=1000, 0<side length<=10000.
import java.util.*;
public class Main {
static int[][]graph;
static final int INF=0x3f3f3f3f;
public static void floyd(int n) {
for(int k=1;k<=n;k++) {
for(int i=1;i<=n;i++) {
for(int j=1;j<=n;j++) {
if(i!=j&&graph[i][j]>graph[i][k]+graph[k][j])
graph[i][j]=graph[i][k]+graph[k][j];
}
}
}
}
public static void main(String[]args) {
Scanner sc=new Scanner(System.in);
int n=sc.nextInt();
graph=new int[n+1][n+1];
for(int i=1;i<=n;i++) {
for(int j=1;j<=n;j++) {
int x=sc.nextInt();
if(x!=0)
graph[i][j]=x;
else graph[i][j]=INF;
}
}
floyd(n);
for(int i=1;i<=n;i++) {
for(int j=1;j<=n;j++) {
if(i!=j&&graph[i][j]!=INF)
System.out.print(graph[i][j]+" ");
else if(i!=j&&graph[i][j]==INF)
System.out.print(-1+" ");
else System.out.print(0+" ");
}
System.out.println();
}
}
}
Referring to other people's code, it should be that reading and writing does not use IO to read and write, resulting in memory timeout
import java.io.*;
public class Main {
public static void main(String[] args) throws NumberFormatException, IOException {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
int n = Integer.parseInt(br.readLine());
int INF = 65535;
int [][]dis = new int[n][n];
for(int i = 0; i < n;i++) {
String[] split = br.readLine().split(" ");
for(int j = 0; j < n;j++) {
if(Integer.parseInt(split[j]) == 0) {
dis[i][j] = INF;
}else {
dis[i][j] = Integer.parseInt(split[j]);
}
}
}
Graph1057 graph = new Graph1057(dis);
graph.floyd();
graph.print();
}
}
class Graph1057{
int n;
int [][]dis;
int INF = 65535;
public Graph1057(int[][] dis) {
this.dis = dis;
n = dis.length;
}
public void floyd() {
for(int k = 0; k < n;k++) {
for(int i = 0; i < n;i++) {
for(int j = 0; j < n;j++) {
int len = dis[i][k] + dis[k][j];
if(len < dis[i][j]) {
dis[i][j] = len;
}
}
}
}
}
public void print() {
for(int i = 0; i < n;i++) {
for(int j = 0; j < n;j++) {
if(i == j) {
System.out.print("0 ");
}else if(dis[i][j] == INF){
System.out.print("-1 ");
}else {
System.out.print(dis[i][j] + " ");
}
}
System.out.println();
}
}
}