2017/4/3

XingwenZhang · XingwenZhang · commit f46c110e817d · 2017-04-03T19:22:19.000-07:00
diff --git a/No374_GuessNumberHigherorLower.cpp b/No374_GuessNumberHigherorLower.cpp
@@ -0,0 +1,46 @@
+// We are playing the Guess Game. The game is as follows:
+
+// I pick a number from 1 to n. You have to guess which number I picked.
+
+// Every time you guess wrong, I'll tell you whether the number is higher or lower.
+
+// You call a pre-defined API guess(int num) which returns 3 possible results (-1, 1, or 0):
+
+// -1 : My number is lower
+//  1 : My number is higher
+//  0 : Congrats! You got it!
+// Example:
+// n = 10, I pick 6.
+
+// Return 6.
+
+
+// Forward declaration of guess API.
+// @param num, your guess
+// @return -1 if my number is lower, 1 if my number is higher, otherwise return 0
+int guess(int num);
+
+class Solution {
+public:
+	// Pay attentation of My number, "My" here means the unknown number
+    int guessNumber(int n) {
+        int low = 1, high = n;
+        int guess_num = 0;
+        while(true){
+            // Overflow
+        	//guess_num = (low + high) / 2;
+        	guess_num = (high-low)/2 + low;
+        	int flag = guess(guess_num);
+        	if(flag == 0){
+        		return guess_num;
+        	}
+        	else if(flag > 0){
+        		low = guess_num + 1;
+        	}
+        	else{
+        		high = guess_num - 1;
+        	}
+
+        }
+    }
+};
