Add 0990 satisfiability of equality equations

begeekmyfriend · begeekmyfriend · commit f88bcf8006a1 · 2023-01-09T19:45:36.000+08:00
Signed-off-by: begeekmyfriend &lt;begeekmyfriend@gmail.com&gt;
diff --git a/0990_satisfiability_of_equality_equations/Makefile b/0990_satisfiability_of_equality_equations/Makefile
@@ -0,0 +1,2 @@
+all:
+	gcc -o test equality_equations.c
diff --git a/0990_satisfiability_of_equality_equations/equality_equations.c b/0990_satisfiability_of_equality_equations/equality_equations.c
@@ -0,0 +1,74 @@
+#include <assert.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+
+struct ufs {
+    int parents[512];
+};
+
+static inline void ufs_init(struct ufs *set)
+{
+    int i;
+    for (i = 0; i < sizeof(set->parents) / sizeof(int); i++) {
+        set->parents[i] = i;
+    }
+}
+
+static inline int ufs_find(struct ufs *set, int node)
+{
+    assert(node >= 0 && node <= sizeof(set->parents) / sizeof(int));
+    if (set->parents[node] != node) {
+        set->parents[node] = ufs_find(set, set->parents[node]);
+    }
+    return set->parents[node];
+}
+
+static inline void ufs_union(struct ufs *set, int p, int q)
+{
+    int root_p, root_q;
+
+    root_p = ufs_find(set, p);
+    root_q = ufs_find(set, q);
+    /* Omit root_p == root_q if-condition */
+    set->parents[root_p] = root_q;
+}
+
+static inline bool ufs_connected(struct ufs *set, int p, int q)
+{
+    return ufs_find(set, p) == ufs_find(set, q);
+}
+
+bool equationsPossible(char ** equations, int equationsSize)
+{
+    int i;
+    struct ufs *set;
+
+    set = malloc(sizeof(*set));
+    ufs_init(set);
+
+    for (i = 0; i < equationsSize; i++) {
+        if (equations[i][1] == '=') {
+            ufs_union(set, equations[i][0], equations[i][3]);
+        }
+    }
+
+    for (i = 0; i < equationsSize; i++) {
+        if (equations[i][1] == '!') {
+            if (ufs_connected(set, equations[i][0], equations[i][3])) {
+                return false;
+            }
+        }
+    }
+
+    return true;
+}
+
+int main(int argc, char **argv)
+{
+    //char *equations[] = {"a==b", "c==c", "x==y" };
+    char *equations[] = {"a==b", "b!=c", "a==c" };
+    printf("%s\n", equationsPossible(equations, sizeof(equations)/sizeof(char *)) ? "true" : "false");
+    return 0;
+}

Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,2 @@`
	`1`	`+all:`
	`2`	`+ gcc -o test equality_equations.c`