Interpolation search

slice_searching/interpolation_search/interpolation_search.go

@@ -0,0 +1,37 @@
+package interpolationsearch
+
+// Runs a search based on interpolation
+func InterpolationSearch(param int, slice []int) int {
+	if param < 0 {
+		return -1
+	}
+	low := 0
+	mid := -1
+	high := len(slice) - 1
+
+	for {
+
+		if low == high || slice[low] == slice[high] {
+			return -1
+		}
+
+		//	 		((Hi -  Lo)/(slice[Hi]  -slice[Lo]     ))*(X-slice[Lo])
+		mid = low + ((high-low)/(slice[high]-slice[low]))*(param-slice[low])
+
+		// where −
+		// 	A    = list
+		// 	Lo   = Lowest index of the list
+		// 	Hi   = Highest index of the list
+		// 	A[n] = Value stored at index n in the list
+
+		if slice[mid] == param {
+			return mid
+		} else {
+			if slice[mid] < param {
+				low = mid + 1
+			} else if slice[mid] > param {
+				high = mid - 1
+			}
+		}
+	}
+}

slice_searching/interpolation_search/interpolation_search_test.go

@@ -0,0 +1,47 @@
+package interpolationsearch
+
+import "testing"
+
+func TestInterpolationSearch(t *testing.T) {
+	type args struct {
+		param int
+		slice []int
+	}
+	tests := []struct {
+		name string
+		args args
+		want int
+	}{
+		{
+			name: "it correctly finds the expected index",
+			args: args{
+				param: 4,
+				slice: []int{2, 4, 6},
+			},
+			want: 1,
+		},
+		{
+			name: "it returns -1 when out of bounds > length",
+			args: args{
+				param: 10,
+				slice: []int{6, 8, 2, 4, 6},
+			},
+			want: -1,
+		},
+		{
+			name: "it returns -1 when mid < 0",
+			args: args{
+				param: -1,
+				slice: []int{6, 8, 2, 4, 6},
+			},
+			want: -1,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := InterpolationSearch(tt.args.param, tt.args.slice); got != tt.want {
+				t.Errorf("InterpolationSearch() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}