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SS_ShortestPaths.java
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51 lines (45 loc) · 1.09 KB
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public class SS_ShortestPaths {
static final int INFINITE = 99999;
public static boolean bellmanFord(int[][] g, int e, int[] d) {
int n = g[0].length; // 列数
int m = g.length; // 行数
d[0] = 0;
for (int i = 1; i < n; i++) {
d[i] = INFINITE;
}
for (int i = 0; i < e - 1; ++i)
for (int j = 0; j < n; ++j)
for (int k = 0; k < m; ++k) {
if (d[j] > d[k] + g[k][j])
d[j] = d[k] + g[k][j];
}
for (int j = 0; j < n; ++j)
for (int k = 0; k < m; ++k) {
if (d[j] > d[k] + g[k][j])
return false;
}
return true;
}
public static void main(String[] args) {
int[][] g = new int[5][5];
for (int i = 0; i < 5; ++i)
for (int j = 0; j < 5; ++j)
g[i][j] = INFINITE;
g[0][1] = -1;
g[0][2] = 3;
g[1][2] = 3;
g[1][3] = 2;
g[1][4] = 2;
g[3][1] = 1;
g[3][2] = 5;
g[4][3] = -3;
int[] shortest = new int[g[0].length];
if (!bellmanFord(g, 8, shortest)) {
System.out.println("存在一个从源点可以到达的权重为负值的环路！");
} else {
for (int i = 0; i < g[0].length; ++i) {
System.out.println("0-" + i + ":" + shortest[i]);
}
}
}
}