add

Author: itning

Leetcode/src/test/java/top/itning/test/LongestCommonPrefixTest.java

@@ -0,0 +1,50 @@
+package top.itning.test;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+/**
+ * 14. 最长公共前缀
+ * 编写一个函数来查找字符串数组中的最长公共前缀。
+ * <p>
+ * 如果不存在公共前缀，返回空字符串 ""。
+ *
+ * @author itning
+ * @since 2021/12/7 14:27
+ */
+public class LongestCommonPrefixTest {
+    @Test
+    void longestCommonPrefixTest() {
+        Assertions.assertEquals("fl", longestCommonPrefix(new String[]{"flower", "flow", "flight"}));
+        Assertions.assertEquals("", longestCommonPrefix(new String[]{"dog", "racecar", "car"}));
+        Assertions.assertEquals("", longestCommonPrefix(new String[]{"", "racecar", "car"}));
+    }
+
+    public String longestCommonPrefix(String[] strs) {
+        // 1 <= strs.length <= 200
+        // 0 <= strs[i].length <= 200
+        // strs[i] 仅由小写英文字母组成
+        int l = Integer.MAX_VALUE;
+        for (String str : strs) {
+            l = Math.min(l, str.length());
+        }
+        if (l == Integer.MAX_VALUE || l == 0) {
+            return "";
+        }
+        StringBuilder sb = new StringBuilder();
+        a:
+        for (int i = 0; i < l; i++) {
+            for (int j = 0; j < strs.length; j++) {
+                char c = strs[j].charAt(i);
+                if (j + 1 != strs.length) {
+                    char cc = strs[j + 1].charAt(i);
+                    if (cc != c) {
+                        break a;
+                    }
+                }
+            }
+            sb.append(strs[0].charAt(i));
+        }
+        return sb.toString();
+    }
+}