leetcode

Author: ayoubzulfiqar

MaximumLengthOfAConcatenatedStringWithUniqueCharacters/maximum_length_of_a_concatenated_string_with_unique_characters.go

@@ -1 +1,104 @@
 package main
+
+func maxLength(arr []string) int {
+	st := make([]int, 0, len(arr))
+	for i := range arr {
+		s := 0
+		f := true
+		for j := range arr[i] {
+			b := 1 << (arr[i][j] - 97)
+			if b&s != 0 {
+				f = false
+				break
+			}
+			s |= b
+		}
+		if f {
+			st = append(st, s)
+		}
+	}
+
+	r := -1
+	var f func(int, int)
+	f = func(i, s int) {
+		cnt := 0
+		ds := s
+		for ds > 0 {
+			cnt += ds & 1
+			ds = ds >> 1
+		}
+		if cnt > r {
+			r = cnt
+		}
+		if i >= len(st) {
+			return
+		}
+		for j := i + 1; j < len(st); j++ {
+			if s&st[j] == 0 {
+				f(j, s|st[j])
+			}
+		}
+	}
+	f(-1, 0)
+	return r
+}
+
+/*
+
+
+
+func maxLength(arr []string) int {
+    masks := make([]int, len(arr))
+    for i, s := range arr {
+        masks[i] = createMask(s)
+    }
+
+    maxLen := 0
+    for i := 0; i < len(arr); i++ {
+        maxLen = max(maxLen, dp(arr, masks, 0, 0, map[int]int{}))
+    }
+
+    return maxLen
+}
+
+func dp(arr []string, masks []int, curMask int, pos int, memo map[int]int) int {
+    if pos == len(arr) {
+        return 0
+    }
+    memoKey := (curMask << 32) | pos
+    if memo[memoKey] > 0 {
+        return memo[memoKey]
+    }
+    maxLen := dp(arr, masks, curMask, pos + 1, memo) // ignoring arr[pos] word
+    if masks[pos] != 0 && (curMask & masks[pos]) == 0 {
+        maxLen = max(
+            maxLen,
+            len(arr[pos]) + dp(arr, masks, curMask | masks[pos], pos + 1, memo),
+        )
+    }
+    memo[memoKey] = maxLen
+    return maxLen
+}
+
+func createMask(s string) int {
+    mask := 0
+    for _, b := range s {
+        add := 1 << (b - 'a')
+        if (mask & add) == add {
+            return 0 // duplicate byte (char)
+        }
+        mask |= add
+    }
+    return mask
+}
+
+func max(a, b int) int {
+    if a > b {
+        return a
+    }
+    return b
+}
+
+
+
+*/