7

Author: retaw

7_reverse_interger.cpp

@@ -0,0 +1,29 @@
+#include "test.h"
+
+class Solution {
+public:
+    int reverse(int x) 
+    {
+        int64_t ret = 0;
+        while(x != 0)
+        {
+            ret *= 10;
+            ret += x % 10;
+
+            if(ret != (int)ret)  //题目要求溢出时返回0
+                return 0;
+
+            x = x / 10;
+
+        }
+        return ret;
+    }
+};
+
+
+int main()
+{
+    Solution s;
+    cout << s.reverse(-32465) << endl;
+    cout << s.reverse(1534236469) << endl; //溢出测试
+}

Makefile

@@ -5,6 +5,7 @@ targets = \
 	4_median_of_two_sorted_arrays.exec\
 	5_longest_palindromic_substring.exec\
 	6_zigzag_conversion.exec\
+	7_reverse_interger.exec\
 
 
 CC = g++

performance.h

@@ -0,0 +1,35 @@
+/*
+ * Author: LiZhaojia 
+ *
+ * Last modified: 2014-09-29 22:01 +0800
+ *
+ * Description: 用于性能测试
+ */
+
+#include <iostream>
+#include <memory>
+#include <functional>
+#include <chrono>
+using namespace std;
+
+void performance ( void (*pfun)(), uint32_t times, std::string info = "" )
+{
+    std::chrono::time_point<std::chrono::high_resolution_clock> start, end;
+
+    cout << "\n\n" << info << " start:" << endl;
+    start = std::chrono::system_clock::now();
+    for(int i = 0; i < times; ++i)
+        (*pfun)();
+    end = std::chrono::system_clock::now();
+
+    std::chrono::duration<double> elapsed_seconds = end-start;
+    std::time_t end_time = std::chrono::system_clock::to_time_t(end);
+
+    std::cout << std::dec << std::fixed 
+    << info
+    << " finished computation at " << std::ctime(&end_time)
+    << "elapsed time: " << elapsed_seconds.count() 
+    << "s; average time: " << elapsed_seconds.count() / times << endl;;
+}
+
+#define PERFORMANCE(fun, times) performance(fun, times, #fun)