Longest valid parentheses

Signed-off-by: begeekmyfriend <[email protected]>

032_longest_valid_parentheses/Makefile

@@ -0,0 +1,2 @@
+all:
+	gcc -O2 -o test valid_parentheses.c

032_longest_valid_parentheses/valid_parentheses.c

@@ -0,0 +1,41 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+static int longestValidParentheses(char* s) {
+    int cap = 1, error = -1;
+    int length = 0, max_length = 0;
+    char *p = s;
+    int *stack = malloc(cap * sizeof(int));
+    int *top = stack;
+
+    while (*s != '\0') {
+        if (*s == '(') {
+            if (top + 1 - stack >= cap) {
+                cap *= 2;
+                stack = realloc(stack, cap * sizeof(int));
+            }
+            *top++ = s - p;
+        } else {
+            if (top > stack) {
+                if (--top == stack) {
+                    length = s - p - error;
+                } else {
+                    length = s - p - *(top - 1);
+                }
+                if (length > max_length) {
+                    max_length = length;
+                }
+            } else {
+                error = s - p;
+            }
+        }
+        s++;
+    }
+    return max_length;
+}
+
+int main(int argc, char **argv)
+{
+    printf("%d\n", longestValidParentheses(argv[1]));
+    return 0;
+}