add new solutions

solutions/37/q3714/solution.go

@@ -0,0 +1,88 @@
+package q3714
+
+func longestBalanced(s string) int {
+	longest := 0
+	single := 0
+	diff3 := make(map[[2]int]int, len(s))
+	diffAB, diffAC := 0, 0
+
+	diff2AB, diff2AC, diff2BC := map[int]int{}, map[int]int{}, map[int]int{}
+	nDiff2AB, nDiff2AC, nDiff2BC := 0, 0, 0
+	lastA, lastB, lastC := -1, -1, -1
+
+	for i := range len(s) {
+		// Single
+		if i > 0 && s[i] == s[i-1] {
+			single++
+		} else {
+			single = 1
+		}
+		longest = max(longest, single)
+
+		// Dual
+		var process2pair = func(diffIdx map[int]int, offset, i, diff int) int {
+			if diff == 0 {
+				return i - offset
+			}
+			if prev, ok := diffIdx[diff]; !ok {
+				diffIdx[diff] = i
+				return 0
+			} else {
+				return i - prev
+			}
+		}
+		switch s[i] {
+		case 'a':
+			lastA = i
+			nDiff2BC, diff2BC = 0, map[int]int{}
+			nDiff2AB++
+			nDiff2AC++
+			t1 := process2pair(diff2AB, lastC, i, nDiff2AB)
+			t2 := process2pair(diff2AC, lastB, i, nDiff2AC)
+			longest = max(longest, t1, t2)
+
+		case 'b':
+			lastB = i
+			nDiff2AC, diff2AC = 0, map[int]int{}
+			nDiff2AB--
+			nDiff2BC++
+			t1 := process2pair(diff2AB, lastC, i, nDiff2AB)
+			t2 := process2pair(diff2BC, lastA, i, nDiff2BC)
+			longest = max(longest, t1, t2)
+
+		case 'c':
+			lastC = i
+			nDiff2AB, diff2AB = 0, map[int]int{}
+			nDiff2BC--
+			nDiff2AC--
+			t1 := process2pair(diff2BC, lastA, i, nDiff2BC)
+			t2 := process2pair(diff2AC, lastB, i, nDiff2AC)
+			longest = max(longest, t1, t2)
+		}
+
+		// Triple
+		switch s[i] {
+		case 'a':
+			diffAB++
+			diffAC++
+		case 'b':
+			diffAB--
+		case 'c':
+			diffAC--
+		}
+		key := [2]int{diffAB, diffAC}
+		if key == [2]int{0, 0} {
+			longest = i + 1
+			continue
+		}
+		if prev, ok := diff3[key]; !ok {
+			diff3[key] = i
+		} else {
+			longest = max(longest, i-prev)
+		}
+	}
+
+	return longest
+}
+
+var _ = longestBalanced