Data update

Task/Stream-merge/Rust/stream-merge.rs

@@ -0,0 +1,81 @@
+use std::cmp::Ordering;
+
+fn merge2<T: Ord + Copy, F: Fn(T)>(c1: &[T], c2: &[T], action: F) {
+    let mut i1 = 0;
+    let mut i2 = 0;
+
+    while i1 < c1.len() && i2 < c2.len() {
+        if c1[i1] <= c2[i2] {
+            action(c1[i1]);
+            i1 += 1;
+        } else {
+            action(c2[i2]);
+            i2 += 1;
+        }
+    }
+
+    while i1 < c1.len() {
+        action(c1[i1]);
+        i1 += 1;
+    }
+
+    while i2 < c2.len() {
+        action(c2[i2]);
+        i2 += 1;
+    }
+}
+
+fn merge_n<T: Ord + Copy, F: Fn(T)>(action: F, all: &[&[T]]) {
+    let mut vit: Vec<(usize, usize)> = all.iter().map(|c| (0, c.len())).collect();
+
+    loop {
+        let mut done = true;
+        let mut least: Option<usize> = None;
+
+        for (i, &(start, end)) in vit.iter().enumerate() {
+            if start < end {
+                if least.is_none() {
+                    least = Some(i);
+                } else {
+                    if let Some(l) = least {
+                        if all[i][start].cmp(&all[l][vit[l].0]) == Ordering::Less {
+                            least = Some(i);
+                        }
+                    }
+                }
+            }
+        }
+
+        if let Some(l) = least {
+            if vit[l].0 < vit[l].1 {
+                done = false;
+                action(all[l][vit[l].0]);
+                vit[l].0 += 1;
+            }
+        }
+
+        if done {
+            break;
+        }
+    }
+}
+
+
+fn display(num: i32) {
+    print!("{} ", num);
+}
+
+fn main() {
+    let v1 = vec![0, 3, 6];
+    let v2 = vec![1, 4, 7];
+    let v3 = vec![2, 5, 8];
+
+    merge2(&v2, &v1, display);
+    println!();
+
+    merge_n(display, &[&v1]);
+    println!();
+
+    merge_n(display, &[&v3, &v2, &v1]);
+    println!();
+}