add merge sort

Author: jamesmarva

code/examples/merge_sort/Cargo.toml

@@ -0,0 +1,9 @@
+[package]
+name = "merge_sort"
+version = "0.1.0"
+authors = ["jameskk <[email protected]>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

code/examples/merge_sort/src/main.rs

@@ -0,0 +1,61 @@
+fn main() {
+    let mut a = [12,232,234,2,34,234,234,2,34,2,34,234,234,2,34,234,2,34,2,34,234,2,34,2];
+    merge_sort_1(&mut a);
+    for i in &a {
+        println!("{}", i);
+    }
+}
+
+pub fn merge_sort_1(arr: &mut [i32]) {
+    // let x = [1, 2, 3];
+    let mut tmp: Vec<i32> = Vec::new();
+    let mut l = arr.len();
+    while l > 0 {
+        tmp.push(0i32);
+        l-=1;
+    }
+    let len = arr.len();
+    merge_core(arr, &mut tmp, 0, (len - 1) as usize);
+}
+fn merge_core(arr: &mut [i32], tmp: &mut [i32], start: usize, end: usize) {
+    if start >= end {
+        return;
+    }
+    let mid = start + ((end - start) >> 1);
+    merge_core(arr, tmp, start, mid);
+    merge_core(arr, tmp, mid + 1, end);
+    merge(arr, tmp, start, mid, end);
+}
+
+fn merge(arr: &mut [i32], tmp: &mut [i32], start: usize, mid: usize, end: usize) {
+    let mut i1 = start;
+    let mut i2 = mid + 1;
+    let mut i = 0;
+    while i1 <= mid && i2 <= end {
+        if arr[i1] <= arr[i2] {
+            tmp[i] = arr[i1];
+            i1+=1;
+        } else {
+            tmp[i] = arr[i2];
+            i2+=1;
+        }
+        i+=1;
+    }
+    while i1 <= mid {
+        tmp[i] = arr[i1];
+        i+=1;
+        i1+=1;
+    }
+    while i2 <= end {
+        tmp[i] = arr[i2];
+        i+=1;
+        i2+=1;
+    }
+
+    let len = i;
+    i = 0;
+    while i < len {
+        arr[start + i] = tmp[i];
+        i+=1;
+    }
+}

code/examples/merge_sort/src/merge_sort.rs

@@ -0,0 +1,35 @@
+pub fn merge_sort<T> (list: &[T]) -> Vec<T>
+    where: T: PartialOrd + Clone + Debug>
+{
+    if list.len() > 1 {
+        let (l, r) = list.split_at(list.len() / 2);
+        let sorted_l = merge_sort(l);
+        let sorted_r = merge_sort(r);
+        let mut rst: Vec<T> = list.into();
+        let (mut i, mut j, mut k) = (0, 0, 0);
+        while i < sorted_l.len() && j < sorted_r.len() {
+            if sorted_l[i] <= sorted_r[j] {
+                rst[k] = sorted_l[i].clone();
+                i += 1;
+            } else {
+                rst[k] = sorted_r[j].clone();
+                j += 1;
+            }
+            k += 1;
+        }
+        while i < sorted_l.len() {
+            rst[k] = sorted_l[i].clone();
+            k += 1;
+            i += 1;
+        }
+
+        while j < sorted_r.len() {
+            rst[k] = sorted_r[j].clone();
+            k += 1;
+            j += 1;
+        }
+        rst
+    } else {
+        list.to_vec()
+    }
+}

code/examples/sort/src/lib.rs

@@ -1,5 +1,5 @@
 pub fn merge_sort_1(arr: &mut [i32]) {
-    let tmp = [0i32; (arr.len() - 1)];
+    let tmp = [0i32; (arr.len() - 1) as usize];
 }
 fn merge_core(arr: &mut [i32], tmp: &mut [i32], start: usize, end: usize) {
     if start >= end {