add problem 14 and test function

Author: supercoderhawk

C/1-50/14-Longest-Common-Prefix.c

@@ -0,0 +1,51 @@
+/*
+ * Write a function to find the longest common prefix string amongst an array of strings.
+ * Created by supercoderx on 2017/8/9.
+ */
+#include 
+#include 
+#include 
+
+char *longestCommonPrefix(char **strs, int strsSize) {
+    char *str = NULL;
+    if (strsSize == 0) {
+        return "";
+    }
+    if (strsSize == 1) {
+        return strs[0];
+    }
+    int lenArr[strsSize], len = 0, minLen = 0, curMinLen = 0;
+
+    for (int i = 0; i < strsSize; i++) {
+        str = strs[i];
+        lenArr[i] = 0;
+        while (*str != '\0') {
+            lenArr[i]++;
+            str++;
+        }
+    }
+    minLen = lenArr[0];
+    for (int i = 1; i < strsSize; i++) {
+        curMinLen = 0;
+        len = lenArr[i] > minLen ? minLen : lenArr[i];
+        for (int j = 0; j < len; j++) {
+            if (strs[i - 1][j] != strs[i][j])
+                break;
+            curMinLen++;
+        }
+        if (curMinLen < minLen)
+            minLen = curMinLen;
+    }
+    if (minLen == 0)
+        return "";
+    str = malloc(sizeof(char) * (minLen + 1));
+    str = strncpy(str, strs[strsSize - 1], minLen);
+    str[minLen] = '\0';
+    return str;
+}
+
+void testLongestCommonPrefix() {
+
+    char *s1[] = {"aa", "b"};
+    printf("%s", longestCommonPrefix(s1, 3));
+}