add problem 20 and test function

Author: supercoderhawk

C/1-50/20-Valid-Parentheses.c

@@ -0,0 +1,63 @@
+/*
+ * Given a string containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.
+ *
+ * The brackets must close in the correct order, "()" and "()[]{}" are all valid but "(]" and "([)]" are not.
+ * Created by supercoderx on 2017/8/9.
+ */
+
+#include <stdio.h>
+#include "../main.h"
+
+bool isValid(char* s) {
+    char* tmp=s;
+    int len = 0, index = -1;
+
+    while (*tmp!='\0'){
+        len++;
+        tmp++;
+    }
+
+    char indicator[len] ;
+    for(int i = 0; i < len;i++){
+        switch (s[i]){
+            case '{':
+                indicator[++index]='{';
+                break;
+            case '}':
+                if(index==-1 || indicator[index]!='{'){
+                    return false;
+                }else{
+                    index--;
+                }
+                break;
+            case '[':
+                indicator[++index]='[';
+                break;
+            case ']':
+                if(index == -1 || indicator[index]!='['){
+                    return false;
+                } else{
+                    index--;
+                }
+                break;
+            case '(':
+                indicator[++index] = '(';
+                break;
+            case ')':
+                if(index == -1 || indicator[index]!='('){
+                    return false;
+                } else{
+                    index--;
+                }
+                break;
+            default:
+                break;
+        }
+    }
+    return index == -1?true:false;
+}
+
+void testIsValid(){
+    char s[] = "[(](";
+    printf("%d",isValid(s));
+}