feat: add binary search

Author: gengjiawen

Cargo.lock

@@ -3,6 +3,7 @@ members = [
     "Array",
     "DP",
     "backtracking",
+    "binary_search",
     "compiler",
     "sliding_window",
     "String",

Cargo.toml

@@ -0,0 +1,11 @@
+[package]
+name = "leetcode_binary_search"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+[lib]
+path = "lib.rs"
+doctest = false
+
+[dependencies]

binary_search/Cargo.toml

@@ -0,0 +1,49 @@
+// https://leetcode.com/problems/binary-search
+//
+// Given an array of integers `nums` which is sorted in ascending order, and an integer `target`, write a function to search `target` in `nums`. If `target` exists, then return its index. Otherwise, return `-1`.
+//
+// You must write an algorithm with `O(log n)` runtime complexity.
+//
+// **Example 1:**
+//
+// ```
+// **Input:** nums = [-1,0,3,5,9,12], target = 9
+// **Output:** 4
+// **Explanation:** 9 exists in nums and its index is 4
+// ```
+//
+// **Example 2:**
+//
+// ```
+// **Input:** nums = [-1,0,3,5,9,12], target = 2
+// **Output:** -1
+// **Explanation:** 2 does not exist in nums so return -1
+// ```
+//
+// **Constraints:**
+//
+// *   `1 <= nums.length <= 10<sup>4</sup>`
+// *   `-10<sup>4</sup> < nums[i], target < 10<sup>4</sup>`
+// *   All the integers in `nums` are **unique**.
+// *   `nums` is sorted in ascending order.
+
+pub fn search(nums: Vec<i32>, target: i32) -> i32 {
+    let mut left = 0;
+    let mut right = nums.len() as i32 - 1;
+    while left <= right {
+        let mid = (left + right) / 2;
+        if nums[mid as usize] == target {
+            return mid;
+        } else if nums[mid as usize] < target {
+            left = mid + 1;
+        } else {
+            right = mid - 1;
+        }
+    }
+    return -1;
+}
+
+#[test]
+pub fn t1() {
+    assert_eq!(search(vec![-1,0,3,5,9,12], 9), 4);
+}

binary_search/_0704_binary_search.rs

@@ -0,0 +1,3 @@
+#![allow(dead_code)]
+
+mod _0704_binary_search;