all tasks

Task/Sorting-algorithms-Counting-sort/Go/sorting-algorithms-counting-sort-1.go

@@ -0,0 +1,45 @@
+package main
+
+import (
+    "fmt"
+    "runtime"
+    "strings"
+)
+
+var a = []int{170, 45, 75, -90, -802, 24, 2, 66}
+var aMin, aMax = -1000, 1000
+
+func main() {
+    fmt.Println("before:", a)
+    countingSort(a, aMin, aMax)
+    fmt.Println("after: ", a)
+}
+
+func countingSort(a []int, aMin, aMax int) {
+    defer func() {
+        if x := recover(); x != nil {
+            // one error we'll handle and print a little nicer message
+            if _, ok := x.(runtime.Error); ok &&
+                strings.HasSuffix(x.(error).Error(), "index out of range") {
+                fmt.Printf("data value out of range (%d..%d)\n", aMin, aMax)
+                return
+            }
+            // anything else, we re-panic
+            panic(x)
+        }
+    }()
+
+    count := make([]int, aMax-aMin+1)
+    for _, x := range a {
+        count[x-aMin]++
+    }
+    z := 0
+    // optimization over task pseudocode:   variable c is used instead of
+    // count[i-min].  This saves some unneccessary calculations.
+    for i, c := range count {
+        for ; c > 0; c-- {
+            a[z] = i + aMin
+            z++
+        }
+    }
+}

Task/Sorting-algorithms-Counting-sort/Go/sorting-algorithms-counting-sort-2.go

@@ -0,0 +1,50 @@
+package main
+
+import (
+    "fmt"
+    "runtime"
+    "strings"
+)
+
+var a = []int{170, 45, 75, -90, -802, 24, 2, 66}
+var aMin, aMax = -1000, 1000
+
+func main() {
+    fmt.Println("before:", a)
+    countingSort(a, aMin, aMax)
+    fmt.Println("after: ", a)
+}
+
+func countingSort(a []int, aMin, aMax int) {
+    defer func() {
+        if x := recover(); x != nil {
+            // one error we'll handle and print a little nicer message
+            if _, ok := x.(runtime.Error); ok &&
+                strings.HasSuffix(x.(error).Error(), "index out of range") {
+                fmt.Printf("data value out of range (%d..%d)\n", aMin, aMax)
+                return
+            }
+            // anything else, we re-panic
+            panic(x)
+        }
+    }()
+
+    // WP algorithm
+    k := aMax - aMin // k is maximum key value. keys range 0..k
+    count := make([]int, k+1)
+    key := func(v int) int { return v - aMin }
+    for _, x := range a {
+        count[key(x)]++
+    }
+    total := 0
+    for i, c := range count {
+        count[i] = total
+        total += c
+    }
+    output := make([]int, len(a))
+    for _, x := range a {
+        output[count[key(x)]] = x
+        count[key(x)]++
+    }
+    copy(a, output)
+}