sqrtx

Author: logerrors

src/sqrtx/bench.cpp

@@ -0,0 +1,51 @@
+#include "solution.hpp"
+
+#include <cmath>
+#include <benchmark/benchmark.h>
+
+float Q_rsqrt( float number )
+{
+	long i;
+	float x2, y;
+	const float threehalfs = 1.5F;
+
+	x2 = number * 0.5F;
+	y  = number;
+	i  = * ( long * ) &y;						// evil floating point bit level hacking
+	i  = 0x5f3759df - ( i >> 1 );               // what the fuck?
+	y  = * ( float * ) &i;
+	y  = y * ( threehalfs - ( x2 * y * y ) );   // 1st iteration
+//	y  = y * ( threehalfs - ( x2 * y * y ) );   // 2nd iteration, this can be removed
+
+#ifndef Q3_VM
+#ifdef __linux__
+	assert( !isnan(y) ); // bk010122 - FPE?
+#endif
+#endif
+	return y;
+}
+
+
+static void BM_mySqrt(benchmark::State& state) {
+    auto s = std::make_shared<Solution>();
+    for (auto _ : state) {
+        s->mySqrt(1233422.0f);
+    }
+}
+
+static void BM_sqrt(benchmark::State& state){
+    for (auto _ : state) {
+        std::sqrt(1233422.0f);
+    }
+}
+
+static void BM_Qsqrt(benchmark::State& state){
+    for (auto _ : state) {
+        Q_rsqrt(1233422.0f);
+    }
+}
+
+// BENCHMARK(BM_mySqrt);
+BENCHMARK(BM_sqrt);
+BENCHMARK(BM_Qsqrt);
+BENCHMARK_MAIN();

src/sqrtx/solution.hpp

@@ -0,0 +1,21 @@
+#include "leetcode.hpp"
+using namespace std;
+
+class Solution {
+public:
+    int mySqrt(int x) {
+        int L = 0;
+        int R = x;
+        int ans = -1;
+        while(L <= R){
+            long mid = L + (R - L)/2;
+            if(mid * mid <= x){
+                ans = mid;
+                L = mid + 1;
+            }else{
+                R = mid - 1;
+            }
+        }
+        return ans;
+    };
+};

src/sqrtx/test.cpp

@@ -0,0 +1,13 @@
+#include "solution.hpp"
+
+#define CATCH_CONFIG_MAIN
+#include <catch2/catch.hpp>
+
+TEST_CASE(__FILE__){
+    auto s = std::make_shared<Solution>();
+
+    SECTION("example"){
+        REQUIRE(s->mySqrt(4) == 2);
+        REQUIRE(s->mySqrt(8) == 2);
+    }
+}

xmake.lua

@@ -43,6 +43,7 @@ define_target("serialize-and-deserialize-binary-tree")
 define_target("merge-intervals")
 define_target("binary-search")
 define_target("guess-number-higher-or-lower")
+define_target("sqrtx")
 
 
 task("problem")