Add problem 312 - Burst Balloons

Author: anirudhology

Diff for: problems/dynamic_programming/burst_balloons.go

@@ -0,0 +1,60 @@
+package dynamic_programming
+
+func BurstBalloons(nums []int) int {
+	// Array to store balloons
+	balloons := make([]int, len(nums)+2)
+	n := len(balloons)
+	balloons[0] = 1
+	balloons[n-1] = 1
+	for i := 1; i < n-1; i++ {
+		balloons[i] = nums[i-1]
+	}
+	// Lookup table
+	lookup := make([][]int, n-1)
+	for i := range lookup {
+		lookup[i] = make([]int, n-1)
+		for j := range lookup[i] {
+			lookup[i][j] = -1
+		}
+	}
+	// Burst all balloons between 1 and n - 2
+	return burst(balloons, 1, n-2, lookup)
+}
+
+func burst(balloons []int, i int, j int, lookup [][]int) int {
+	// Base case
+	if i > j {
+		return 0
+	}
+	// If there is only one balloon
+	if i == j {
+		temp := balloons[i]
+		if i-1 >= 0 {
+			temp = temp * balloons[i-1]
+		}
+		if j+1 < len(balloons) {
+			temp = temp * balloons[j+1]
+		}
+		return temp
+	}
+	// If we have already calculated this result
+	if lookup[i][j] != -1 {
+		return lookup[i][j]
+	}
+	// Score
+	score := 0
+	// Burst all balloons between range i...j
+	for k := i; k <= j; k++ {
+		temp := balloons[k]
+		if i-1 >= 0 {
+			temp = temp * balloons[i-1]
+		}
+		if j+1 < len(balloons) {
+			temp = temp * balloons[j+1]
+		}
+		temp += (burst(balloons, i, k-1, lookup)) + (burst(balloons, k+1, j, lookup))
+		score = max(score, temp)
+	}
+	lookup[i][j] = score
+	return score
+}

Diff for: tests/dynamic_programming/burst_balloons_test.go

@@ -0,0 +1,42 @@
+package dynamic_programming_test
+
+import (
+	"testing"
+
+	"github.com/anirudhology/leetcode-go/problems/dynamic_programming"
+)
+
+func TestMaxCoinsSingleBalloon(t *testing.T) {
+	nums := []int{5}
+	if result := dynamic_programming.BurstBalloons(nums); result != 5 {
+		t.Errorf("Expected 5, got %d", result)
+	}
+}
+
+func TestMaxCoinsTwoBalloons(t *testing.T) {
+	nums := []int{3, 1}
+	if result := dynamic_programming.BurstBalloons(nums); result != 6 {
+		t.Errorf("Expected 6, got %d", result)
+	}
+}
+
+func TestMaxCoinsMultipleBalloons(t *testing.T) {
+	nums := []int{3, 1, 5, 8}
+	if result := dynamic_programming.BurstBalloons(nums); result != 167 {
+		t.Errorf("Expected 167, got %d", result)
+	}
+}
+
+func TestMaxCoinsNoBalloons(t *testing.T) {
+	nums := []int{}
+	if result := dynamic_programming.BurstBalloons(nums); result != 0 {
+		t.Errorf("Expected 0, got %d", result)
+	}
+}
+
+func TestMaxCoinsLargeCase(t *testing.T) {
+	nums := []int{1, 2, 3, 4, 5, 6}
+	if result := dynamic_programming.BurstBalloons(nums); result != 252 {
+		t.Errorf("Expected 252, got %d", result)
+	}
+}