From 6567568a60897ea9792d41f9089d392157cd1c6a Mon Sep 17 00:00:00 2001
From: begeekmyfriend <begeekmyfriend@gmail.com>
Date: Wed, 2 Aug 2017 10:55:38 +0800
Subject: [PATCH] Valid parentheses

Signed-off-by: begeekmyfriend <begeekmyfriend@gmail.com>
---
 020_valid_parentheses/Makefile            |  2 +
 020_valid_parentheses/valid_parentheses.c | 47 +++++++++++++++++++++++
 2 files changed, 49 insertions(+)
 create mode 100644 020_valid_parentheses/Makefile
 create mode 100644 020_valid_parentheses/valid_parentheses.c

diff --git a/020_valid_parentheses/Makefile b/020_valid_parentheses/Makefile
new file mode 100644
index 0000000..04fa256
--- /dev/null
+++ b/020_valid_parentheses/Makefile
@@ -0,0 +1,2 @@
+all:
+	gcc -O2 -o test valid_parentheses.c
diff --git a/020_valid_parentheses/valid_parentheses.c b/020_valid_parentheses/valid_parentheses.c
new file mode 100644
index 0000000..8fa87c8
--- /dev/null
+++ b/020_valid_parentheses/valid_parentheses.c
@@ -0,0 +1,47 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+
+static bool isValid(char *s)
+{
+    int n = 0, cap = 100;
+    char *stack = malloc(cap);
+
+    while (*s != '\0') {
+        switch(*s) {
+        case '(':
+        case '[':
+        case '{':
+            if (n + 1 >= cap) {
+                cap *= 2;
+                stack = realloc(stack, cap);
+            }
+            stack[n++] = *s;
+            break;
+        case ')':
+            if (stack[--n] != '(') return false;
+            break;
+        case ']':
+            if (stack[--n] != '[') return false;
+            break;
+        case '}':
+            if (stack[--n] != '{') return false;
+            break;
+        default:
+            return false;
+        }
+        s++;
+    }
+
+    return n == 0;
+}
+
+int main(int argc, char **argv)
+{
+    if (argc != 2) {
+        fprintf(stderr, "Usage: ./test xxxx");
+        exit(-1);
+    }
+    printf("%s\n", isValid(argv[1]) ? "true" : "false");
+    return 0;
+}