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authorjack <[email protected]>2024-06-14 13:13:15 -0600
committerjack <[email protected]>2024-06-14 13:13:15 -0600
commitd343a3b18dbaca9297d4f7b2280c4a16f0a5c8aa (patch)
tree96df922dae2a5073d9a50ea70c7aae6aa37e3ebe /valid_stack_seq.c
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+// 946. Validate Stack Sequences
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+/*
+ * given two integer arrays 'pushed' & 'popped' each with distinct
+ * values, return true if this could have been the result of a sequence
+ * of push and pop operations on an initially empty stack, or false otherwise
+ */
+
+bool validateStackSequences(int *pushed, int pushed_size, int *popped,
+ int popped_size) {
+ int i = 0, j = 0, k = 0;
+ int *s = (int *)malloc(pushed_size * sizeof(int));
+ while (k >= 0 && k < pushed_size && j < popped_size) {
+ if (k > 0 && s[k - 1] == popped[j]) {
+ k--;
+ j++;
+ } else {
+ if (i < pushed_size) {
+ if (pushed[i] == popped[j]) {
+ i++;
+ j++;
+ } else
+ s[k++] = pushed[i++];
+ } else {
+ free(s);
+ return false;
+ }
+ }
+ }
+ free(s);
+ return true;
+}
+
+int main() {
+ int pushed[] = {1, 2, 3, 4, 5};
+ int p1[] = {4, 5, 3, 2, 1}, p2[] = {4, 3, 5, 1, 2};
+ printf("%d\n", validateStackSequences(pushed, 5, p1, 5)); // expect: 1
+ printf("%d\n", validateStackSequences(pushed, 5, p2, 5)); // expect: 0
+}