add new solutions

solutions/7/q761/solution.go

@@ -0,0 +1,84 @@
+package q761
+
+func toNumber(arrs ...[]byte) int {
+	r := 0
+	for i := range arrs {
+		for _, num := range arrs[i] {
+			r = r<<1 + int(num)
+		}
+	}
+	return r
+}
+
+func fromNumber(arr []byte, num int) {
+	for i := len(arr) - 1; i >= 0; i-- {
+		arr[i] = byte(num % 2)
+		num >>= 1
+	}
+}
+
+func move(arr []byte) int {
+	specials := [][2]int{}
+	specialsMap := make(map[int][]int, len(arr)+1)
+	val := toNumber(arr)
+
+	for i := range len(arr) - 1 {
+		if arr[i] == 0 {
+			continue
+		}
+		bal := 1
+		for j := i + 1; j < len(arr); j++ {
+			switch arr[j] {
+			case 0:
+				bal--
+			case 1:
+				bal++
+			}
+
+			if bal < 0 {
+				break
+			}
+			if bal == 0 {
+				specials = append(specials, [2]int{i, j})
+				specialsMap[i] = append(specialsMap[i], j)
+			}
+		}
+	}
+
+	for i := range specials {
+		l1, r1 := specials[i][0], specials[i][1]
+		l2 := r1 + 1
+		for _, r2 := range specialsMap[l2] {
+			swapped := toNumber(arr[:l1], arr[l2:r2+1], arr[l1:l2], arr[r2+1:])
+			if swapped > val {
+				val = swapped
+			}
+		}
+	}
+	return val
+}
+
+func makeLargestSpecial(s string) string {
+	arr := []byte(s)
+	for i := range arr {
+		arr[i] -= '0'
+	}
+
+	val := toNumber(arr)
+	for {
+		newVal := move(arr)
+		if newVal > val {
+			val = newVal
+			fromNumber(arr, newVal)
+		} else {
+			break
+		}
+	}
+
+	for i := range arr {
+		arr[i] += '0'
+	}
+	return string(arr)
+}
+
+var _ = makeLargestSpecial