Graph

2026-09-07 18:48:16 +08:00
parent 1564716731
commit c945aa211f
138 changed files with 10337 additions and 150 deletions
@@ -0,0 +1,70 @@
+#include "c_Test.h"
+#include "c_EdgeWeightedDigraph.h"
+#include "c_BellmanFordSP.h"
+
+TEST_CASE(test_bellman_ford_shortest_path_negative_weights) {
+    c_EdgeWeightedDigraph_t g;
+    c_EdgeWeightedDigraph_Init(&g, 4, NULL);
+
+    /* Construct a graph with negative weights but NO negative cycles:
+     * 0 -> 1 (Weight:  5.0)
+     * 0 -> 2 (Weight:  2.0)
+     * 2 -> 1 (Weight: -4.0) -> Shortest path to 1 is 0->2->1 (Total: -2.0)
+     * 1 -> 3 (Weight:  3.0) -> Shortest path to 3 is 0->2->1->3 (Total: 1.0)
+     */
+    c_EdgeWeightedDigraph_AddEdge(&g, 0, 1,  5.0);
+    c_EdgeWeightedDigraph_AddEdge(&g, 0, 2,  2.0);
+    c_EdgeWeightedDigraph_AddEdge(&g, 2, 1, -4.0);
+    c_EdgeWeightedDigraph_AddEdge(&g, 1, 3,  3.0);
+
+    c_BellmanFordSP_t sp;
+    c_err_t err = c_BellmanFordSP_Init(&sp, &g, 0, &g.allocator);
+    ASSERT_INT_EQ(C_SUCCESS, err);
+
+    ASSERT_FALSE(c_BellmanFordSP_HasNegativeCycle(&sp));
+    ASSERT_TRUE(c_BellmanFordSP_HasPathTo(&sp, 3));
+    ASSERT_DOUBLE_EQ_MSG(-2.0, c_BellmanFordSP_DistTo(&sp, 1), "Shortest path to 1 wrong");
+    ASSERT_DOUBLE_EQ_MSG(1.0,  c_BellmanFordSP_DistTo(&sp, 3), "Shortest path to 3 wrong");
+
+    c_BellmanFordSP_Destroy(&sp);
+    c_EdgeWeightedDigraph_Destroy(&g);
+}
+
+TEST_CASE(test_bellman_ford_negative_cycle_detection) {
+    c_EdgeWeightedDigraph_t g;
+    c_EdgeWeightedDigraph_Init(&g, 3, NULL);
+
+    /* Construct a graph with a negative cycle loop:
+     * 0 -> 1 (Weight:  2.0)
+     * 1 -> 2 (Weight: -1.0)
+     * 2 -> 1 (Weight: -2.0) -> Cycle 1->2->1 has total weight -3.0 (Negative Cycle!)
+     */
+    c_EdgeWeightedDigraph_AddEdge(&g, 0, 1,  2.0);
+    c_EdgeWeightedDigraph_AddEdge(&g, 1, 2, -1.0);
+    c_EdgeWeightedDigraph_AddEdge(&g, 2, 1, -2.0);
+
+    c_BellmanFordSP_t sp;
+    c_err_t err = c_BellmanFordSP_Init(&sp, &g, 0, &g.allocator);
+    ASSERT_INT_EQ(C_SUCCESS, err);
+
+    /* The negative cycle must be caught successfully */
+    ASSERT_TRUE(c_BellmanFordSP_HasNegativeCycle(&sp));
+
+    c_VertexIdList_t cycle_loop;
+    c_VertexIdList_Init(&cycle_loop, 0, 0);
+    err = c_BellmanFordSP_GetNegativeCycle(&sp, &cycle_loop);
+    ASSERT_INT_EQ(C_SUCCESS, err);
+    ASSERT_TRUE(c_VertexIdList_GetSize(&cycle_loop) > 0);
+
+    c_VertexIdList_Destroy(&cycle_loop);
+    c_BellmanFordSP_Destroy(&sp);
+    c_EdgeWeightedDigraph_Destroy(&g);
+}
+
+int main(void) {
+    TEST_START(BellmanFordSP_Engine_Suite);
+    RUN_TEST(test_bellman_ford_shortest_path_negative_weights);
+    RUN_TEST(test_bellman_ford_negative_cycle_detection);
+    TEST_REPORT();
+    RETURN_TEST_STATUS;
+}