commit

Author: 王俊超

.idea/modules.xml

@@ -0,0 +1,39 @@
+/**
+ * <pre>
+ * The isBadVersion API is defined in the parent class VersionControl.
+ *       boolean isBadVersion(int version);
+ * </pre>
+ *
+ * @author: wangjunchao(王俊超)
+ * @time: 2018-10-10 14:26
+ **/
+public class Solution extends VersionControl {
+    public int firstBadVersion(int n) {
+
+        if (!isBadVersion(n)) {
+            return 0;
+        }
+
+        int hi = n;
+        int lo = 1;
+        int mid;
+
+        while (hi >= lo) {
+            mid = lo + (hi - lo) / 2;
+            if (isBadVersion(mid)) {
+                // 当前是1号版本，或者前一个是合法版本，那么当前版本就是第一个非法的版本
+                if (mid == 1 || (mid > 1 && !isBadVersion(mid - 1))) {
+                    return mid;
+                } else {
+                    // 非法的版本在[lo, mid-1]间
+                    hi = mid - 1;
+                }
+            } else {
+                // 非法版本在[mid + 1, hi]间
+                lo = mid + 1;
+            }
+        }
+
+        return 0;
+    }
+}

【278】【First Bad Version】/src/Solution.java

@@ -0,0 +1,12 @@
+/**
+ * @author: wangjunchao(王俊超)
+ * @time: 2018-10-10 16:55
+ **/
+public class Test {
+    public static void main(String[] args) {
+        Solution solution = new Solution();
+
+        solution.setBadVersion(new boolean[]{false, false, false, true, true});
+        System.out.println(solution.firstBadVersion(5));
+    }
+}

【278】【First Bad Version】/src/Test.java

@@ -0,0 +1,20 @@
+/**
+ * @author: wangjunchao(王俊超)
+ * @time: 2018-10-10 14:27
+ **/
+public class VersionControl {
+
+    private boolean[] badVersion;
+
+    public boolean isBadVersion(int version){
+        return badVersion[version - 1];
+    }
+
+    public boolean[] getBadVersion() {
+        return badVersion;
+    }
+
+    public void setBadVersion(boolean[] badVersion) {
+        this.badVersion = badVersion;
+    }
+}