feat(geektime_algo): add 15 binary search

rust/15_binary_search/binary_search.rs

@@ -0,0 +1,46 @@
+// 二分查找
+pub fn binary_search(nums: Vec<i32>, value: i32) -> i32 {
+    if nums.is_empty() { return -1; }
+
+    let mut low = 0;
+    let mut high = nums.len() - 1;
+
+    while low <= high {
+        let mid = low + ((high - low) >> 1);
+        if nums[mid] == value { return mid as i32; }
+
+        if nums[mid] < value {
+            low = mid + 1;
+        } else {
+            high = mid -1;
+        }
+    }
+    -1
+}
+
+// 二分查找递归
+pub fn binary_search_recursion(nums: Vec<i32>, value: i32) -> i32 {
+    if nums.is_empty() { return -1; }
+
+    _recursion(&nums, 0, nums.len()-1, value)
+}
+
+fn _recursion(nums: &Vec<i32>, low: usize, high: usize, value: i32) -> i32 {
+    if low > high { return -1; }
+
+    let mid = low + ((high - low) >> 1);
+    if nums[mid] == value { return mid as i32; }
+
+    if nums[mid] < value {
+        return _recursion(nums, mid+1, high, value);
+    } else {
+        return _recursion(nums, low, mid-1, value);
+    }
+}
+
+fn main() {
+    let nums1 = vec![8,11,19,23,27,33,45,55,67,98];
+    let nums2 = vec![8,11,19,23,27,33,45,55,67,98];
+    println!("{:?}", binary_search(nums1, 23));
+    println!("{:?}", binary_search_recursion(nums2, 23));
+}

rust/15_binary_search/sqrtx.rs

@@ -0,0 +1,28 @@
+// leetcode: https://leetcode.com/problems/sqrtx/
+
+pub fn my_sqrt(x: i32, precision: f32) -> f32 {
+    if x == 0 || x == 1 { return x as f32; }
+
+    let mut left = 0f32;
+    let mut right = x as f32;
+    let mut res = 0f32;
+
+    while left <= right {
+        let mid: f32 = (right - left) / 2.0 + left;
+
+        if (right - left).abs() < precision { return mid; }
+
+        if mid > x as f32 / mid {
+            right = mid;
+        } else {
+            left = mid;
+        }
+        res = mid
+    }
+
+    res
+}
+
+fn main() {
+    println!("{:?}", my_sqrt(8, 0.000001));
+}