all tasks

Task/Sorting-algorithms-Merge-sort/Tcl/sorting-algorithms-merge-sort.tcl

@@ -0,0 +1,33 @@
+package require Tcl 8.5
+
+proc mergesort m {
+    set len [llength $m]
+    if {$len <= 1} {
+        return $m
+    }
+    set middle [expr {$len / 2}]
+    set left [lrange $m 0 [expr {$middle - 1}]]
+    set right [lrange $m $middle end]
+    return [merge [mergesort $left] [mergesort $right]]
+}
+
+proc merge {left right} {
+    set result [list]
+    while {[set lleft [llength $left]] > 0 && [set lright [llength $right]] > 0} {
+        if {[lindex $left 0] <= [lindex $right 0]} {
+            set left [lassign $left value]
+        } else {
+            set right [lassign $right value]
+        }
+        lappend result $value
+    }
+    if {$lleft > 0} {
+        lappend result {*}$left
+    }
+    if {$lright > 0} {
+        set result [concat $result $right] ;# another way append elements
+    }
+    return $result
+}
+
+puts [mergesort {8 6 4 2 1 3 5 7 9}] ;# => 1 2 3 4 5 6 7 8 9