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Commit f88bcf8

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Add 0990 satisfiability of equality equations
Signed-off-by: begeekmyfriend <begeekmyfriend@gmail.com>
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all:
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gcc -o test equality_equations.c
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#include <assert.h>
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#include <stdbool.h>
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#include <stdio.h>
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#include <stdlib.h>
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struct ufs {
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int parents[512];
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};
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static inline void ufs_init(struct ufs *set)
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{
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int i;
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for (i = 0; i < sizeof(set->parents) / sizeof(int); i++) {
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set->parents[i] = i;
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}
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}
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static inline int ufs_find(struct ufs *set, int node)
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{
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assert(node >= 0 && node <= sizeof(set->parents) / sizeof(int));
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if (set->parents[node] != node) {
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set->parents[node] = ufs_find(set, set->parents[node]);
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}
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return set->parents[node];
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}
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static inline void ufs_union(struct ufs *set, int p, int q)
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{
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int root_p, root_q;
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root_p = ufs_find(set, p);
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root_q = ufs_find(set, q);
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/* Omit root_p == root_q if-condition */
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set->parents[root_p] = root_q;
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}
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static inline bool ufs_connected(struct ufs *set, int p, int q)
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{
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return ufs_find(set, p) == ufs_find(set, q);
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}
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bool equationsPossible(char ** equations, int equationsSize)
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{
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int i;
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struct ufs *set;
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set = malloc(sizeof(*set));
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ufs_init(set);
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for (i = 0; i < equationsSize; i++) {
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if (equations[i][1] == '=') {
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ufs_union(set, equations[i][0], equations[i][3]);
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}
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}
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for (i = 0; i < equationsSize; i++) {
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if (equations[i][1] == '!') {
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if (ufs_connected(set, equations[i][0], equations[i][3])) {
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return false;
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}
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}
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}
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return true;
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}
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int main(int argc, char **argv)
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{
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//char *equations[] = {"a==b", "c==c", "x==y" };
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char *equations[] = {"a==b", "b!=c", "a==c" };
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printf("%s\n", equationsPossible(equations, sizeof(equations)/sizeof(char *)) ? "true" : "false");
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return 0;
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}

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