FirstBadVersion

src/com/bzh/leetcode/sort_search/FirstBadVersion.java

@@ -0,0 +1,28 @@
+package com.bzh.leetcode.sort_search;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class FirstBadVersion {
+    boolean isBadVersion(int version) {
+        return version >= 2;
+    }
+
+    @Test
+    public void tst() {
+        Assert.assertEquals(2, firstBadVersion(100));
+    }
+
+    //https://www.zhihu.com/question/36132386
+    public int firstBadVersion(int n) {
+
+        int left = 1, right = n;
+        while (left <= right) {
+            int mid = left + (right - left) / 2;
+            if (isBadVersion(mid)) right = mid-1;
+            else left = mid+1;
+        }
+        return left;
+    }
+
+}