Solve leetcode 33

src/lc33.rs

@@ -0,0 +1,75 @@
+#[cfg(test)]
+use std::cmp::Ordering;
+
+#[cfg(test)]
+struct Solution;
+
+#[cfg(test)]
+impl Solution {
+    pub fn search(nums: Vec<i32>, target: i32) -> i32 {
+        if nums.len() == 1 {
+            return if nums[0] == target { 0 } else { -1 };
+        }
+        if !has_rotation(&nums) {
+            return binary_search(&nums, target, 0, nums.len() - 1);
+        }
+        let p = find_pivot(&nums);
+        return if target >= nums[0] && target <= nums[p.floor() as usize] {
+            // target is in left side
+            binary_search(&nums, target, 0, p.floor() as usize)
+        } else {
+            // target is in right side
+            binary_search(&nums, target, p.ceil() as usize, nums.len() - 1)
+        };
+    }
+}
+
+#[cfg(test)]
+fn has_rotation(n: &[i32]) -> bool {
+    return n[0] > n[n.len() - 1];
+}
+
+#[cfg(test)]
+fn find_pivot(n: &[i32]) -> f32 {
+    let (mut l, mut r) = (0, n.len() - 1);
+    while r != l + 1 {
+        let m = (l + r) as f32 / 2f32;
+        if n[l] > n[m.floor() as usize] {
+            // there is a pivot between i and m
+            r = m.ceil() as usize;
+        } else {
+            // there is a pivot between m and j
+            l = m.floor() as usize;
+        }
+    }
+    return (l + r) as f32 / 2f32;
+}
+
+#[cfg(test)]
+fn binary_search(n: &[i32], t: i32, l: usize, r: usize) -> i32 {
+    if n[l] > t || t > n[r] {
+        return -1;
+    }
+    if l == r {
+        return l as i32;
+    }
+    let m = (l + r) / 2;
+    match t.cmp(&n[m]) {
+        Ordering::Equal => binary_search(n, t, m, m),
+        Ordering::Less => binary_search(n, t, l, m - 1),
+        Ordering::Greater => binary_search(n, t, m + 1, r),
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_search() {
+        assert_eq!(4, Solution::search(vec![4, 5, 6, 7, 0, 1, 2], 0));
+        assert_eq!(-1, Solution::search(vec![4, 5, 6, 7, 0, 1, 2], 3));
+        assert_eq!(-1, Solution::search(vec![1], 0));
+        assert_eq!(-1, Solution::search(vec![1, 3, 5], 2));
+    }
+}

src/lib.rs

@@ -9,3 +9,4 @@ pub mod lc739;
 pub mod lc572;
 pub mod lc853;
 pub mod lc875;
+pub mod lc33;