add 69

Author: cch123

S0069-sqrtx/Cargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "S0069-sqrtx"
+version = "0.1.0"
+authors = ["xargin <cao1988228@163.com>"]
+edition = "2018"
+
+[dependencies]

S0069-sqrtx/src/main.rs

@@ -0,0 +1,18 @@
+fn main() {
+    println!("Hello, world!");
+}
+
+struct Solution;
+//https://en.wikipedia.org/wiki/Integer_square_root#Using_only_integer_division
+impl Solution {
+    pub fn my_sqrt(x: i32) -> i32 {
+        let x = x as f64;
+        let (mut a1, mut a2) = (1.0f64, 0.0f64);
+
+        while (a1 - a2).abs() >= 0.1 {
+            a2 = a1;
+            a1 = (a1 + x / a1) / 2.0;
+        }
+        a1 as i32
+    }
+}