Merge 06511a3 into 6f01f38

README.md

@@ -454,4 +454,5 @@ problems from
 * [Day 454](https://github.com/vaskoz/dailycodingproblem-go/issues/917)
 * [Day 455](https://github.com/vaskoz/dailycodingproblem-go/issues/919)
 * [Day 456](https://github.com/vaskoz/dailycodingproblem-go/issues/921)
+* [Day 457](https://github.com/vaskoz/dailycodingproblem-go/issues/923)
 

day457/problem.go

@@ -0,0 +1,28 @@
+package day457
+
+import "reflect"
+
+// StartIndicesAnagrams returns all the starting indices (0-based)
+// for the anagrams of W in the longer string S.
+// Runs in O(N*M) time where N is len(word) and M is len(str).
+func StartIndicesAnagrams(w string, s string) []int {
+	freq := make(map[rune]int)
+	for _, r := range w {
+		freq[r]++
+	}
+
+	var result []int
+
+	for i := range s {
+		sub := make(map[rune]int)
+		for j := i; j < len(s) && j < i+len(w); j++ {
+			sub[rune(s[j])]++
+		}
+
+		if reflect.DeepEqual(sub, freq) {
+			result = append(result, i)
+		}
+	}
+
+	return result
+}

day457/problem_test.go

@@ -0,0 +1,33 @@
+package day457
+
+import (
+	"reflect"
+	"testing"
+)
+
+// nolint
+var testcases = []struct {
+	W, S     string
+	expected []int
+}{
+	{"ab", "abxaba", []int{0, 3, 4}},
+	{"ba", "abxaba", []int{0, 3, 4}},
+	{"aabx", "abxaba", []int{0, 2}},
+}
+
+func TestStartIndicesAnagrams(t *testing.T) {
+	t.Parallel()
+
+	for _, tc := range testcases {
+		if result := StartIndicesAnagrams(tc.W, tc.S); !reflect.DeepEqual(tc.expected, result) {
+			t.Errorf("Expected %v got %v", tc.expected, result)
+		}
+	}
+}
+func BenchmarkStartIndicesAnagrams(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		for _, tc := range testcases {
+			StartIndicesAnagrams(tc.W, tc.S)
+		}
+	}
+}