Floyd(最短路径问题）

#include <iostream>
#include <cstdio>
#include <cstring>
#define INF 0x7ffffff//如果设为0x7fffffff在执行算法时溢出。
#define maxn 100
using namespace std;
int n;
int edge[maxn][maxn];
int a[maxn][maxn], path[maxn][maxn];

void floyd() {
    int i, j, k;
    for( i = 0; i < n; i++ ) {
        for( j = 0; j < n; j++) {
            a[i][j] = edge[i][j];
            if( i != j && a[i][j] < INF ) { path[i][j] = i; }
            else { path[i][j] = -1; }
        }
    }
    for( k = 0; k < n; k++ ) {
        for( i = 0; i < n; i++ ) {
            for( j = 0; j < n; j++ ) {
                if( k == i || k == j ) { continue; }
                if( a[i][k] + a[k][j] < a[i][j] ) {
                    a[i][j] = a[i][k] + a[k][j];
                    path[i][j] = path[k][j];
                }
            }
        }
   }
}

void output() {
    int i, j;
    int shortest[maxn];
    for( i = 0; i < n; i++ ) {
        for( j = 0; j < n; j++ ) {
            if( i == j) { continue; }
            printf( "%d->%d\t%d\t", i, j, a[i][j] );
            memset( shortest, 0, sizeof(shortest) );
            int k = 0;
            shortest[k] = j;
            while( path[i][shortest[k]] != i) {
                k++; shortest[k] = path[i][shortest[k-1]];
            }
            k++; shortest[k] = i;
            for( int t = k; t >0; t-- ) {
                printf( "%d->", shortest[t] );
            }
            printf( "%d\n",shortest[0] );
        }
    }
    return;
}

void init() {
    int i, j;
    int u, v, w;
    scanf("%d", &n);
    for( i = 0; i < n; i++ ) {
        for( j = 0; j < n; j++ ) {
            if(i != j) { edge[i][j] = INF; }
            else { edge[i][j] = 0; }
        }
    }
    while( 1 ) {
        scanf("%d%d%d", &u, &v, &w);
        if( u == -1 && v == -1 && w == -1 ) { break; }
        edge[u][v] = w;
    }
}

int main()
{
    init();
    floyd();
    output();
    return 0;
}
/**************************
测试数据：
4
0 1 1
0 3 4
1 2 9
1 3 2
2 0 3
2 1 5
2 3 8
3 2 6
-1 -1 -1
***********************/