We have been given N balloons, each with a number of coins associated with it. On bursting a balloon i, the number of coins gained is equal to A[i-1]*A[i]*A[i+1]. Also, balloons i-1 and i+1 now become adjacent. Find the maximum possible profit earned after bursting all the balloons. Assume an extra 1 at each boundary.
Examples:
Input : 5, 10
Output : 60
Explanation - First Burst 5, Coins = 1*5*10
Then burst 10, Coins+= 1*10*1
Total = 60
Input : 1, 2, 3, 4, 5
Output : 110
A recursive solution is discussed here. We can solve this problem using dynamic programming.
First, consider a sub-array from indices Left to Right(inclusive).
If we assume the balloon at index Last to be the last balloon to be burst in this sub-array, we would say the coined gained to be-A[left-1]*A[last]*A[right+1].
Also, the total Coin Gained would be this value, plus dp[left][last – 1] + dp[last + 1][right], where dp[i][j] means maximum coin gained for sub-array with indices i, j.
Therefore, for each value of Left and Right, we need find and choose a value of Last with maximum coin gained, and update the dp array.
Our Answer is the value at dp[1][N].
C++
#include <bits/stdc++.h>
#include <iostream>
using namespace std;
int getMax( int A[], int N)
{
int B[N + 2];
B[0] = 1;
B[N + 1] = 1;
for ( int i = 1; i <= N; i++)
B[i] = A[i - 1];
int dp[N + 2][N + 2];
memset (dp, 0, sizeof (dp));
for ( int length = 1; length < N + 1; length++)
{
for ( int left = 1; left < N - length + 2; left++)
{
int right = left + length - 1;
for ( int last = left; last < right + 1; last++)
{
dp[left][right] = max(dp[left][right],
dp[left][last - 1] +
B[left - 1] * B[last] * B[right + 1] +
dp[last + 1][right]);
}
}
}
return dp[1][N];
}
int main()
{
int A[] = { 1, 2, 3, 4, 5 };
int N = sizeof (A) / sizeof (A[0]);
cout << getMax(A, N) << endl;
}
|
Java
import java.util.Arrays;
class GFG{
public static int getMax( int [] A, int N)
{
int [] B = new int [N + 2 ];
B[ 0 ] = B[N + 1 ] = 1 ;
for ( int i = 1 ; i <= N; i++)
B[i] = A[i - 1 ];
int [][] dp = new int [N + 2 ][N + 2 ];
for ( int length = 1 ;
length < N + 1 ; length++)
{
for ( int left = 1 ;
left < N - length + 2 ; left++)
{
int right = left + length - 1 ;
for ( int last = left;
last < right + 1 ; last++)
{
dp[left][right] = Math.max(
dp[left][right],
dp[left][last - 1 ] +
B[left - 1 ] * B[last] *
B[right + 1 ] +
dp[last + 1 ][right]);
}
}
}
return dp[ 1 ][N];
}
public static void main(String args[])
{
int [] A = { 1 , 2 , 3 , 4 , 5 };
int N = A.length;
System.out.println(getMax(A, N));
}
}
|
Python3
def getMax(A):
N = len (A)
A = [ 1 ] + A + [ 1 ]
dp = [[ 0 for x in range (N + 2 )] for y in range (N + 2 )]
for length in range ( 1 , N + 1 ):
for left in range ( 1 , N - length + 2 ):
right = left + length - 1
for last in range (left, right + 1 ):
dp[left][right] = max (dp[left][right], \
dp[left][last - 1 ] + \
A[left - 1 ] * A[last] * A[right + 1 ] + \
dp[last + 1 ][right])
return (dp[ 1 ][N])
A = [ 1 , 2 , 3 , 4 , 5 ]
print (getMax(A))
|
C#
using System;
class GFG{
public static int getMax( int [] A, int N)
{
int [] B = new int [N + 2];
B[0] = B[N + 1] = 1;
for ( int i = 1; i <= N; i++)
B[i] = A[i - 1];
int [,] dp = new int [(N + 2), (N + 2)];
for ( int length = 1;
length < N + 1; length++)
{
for ( int left = 1;
left < N - length + 2; left++)
{
int right = left + length -1;
for ( int last = left;
last < right + 1; last++)
{
dp[left, right] = Math.Max(
dp[left, right],
dp[left, last - 1] +
B[left - 1] * B[last] *
B[right + 1] +
dp[last + 1, right]);
}
}
}
return dp[1, N];
}
public static void Main()
{
int [] A = new int [] { 1, 2, 3, 4, 5 };
int N = A.Length;
Console.WriteLine(getMax(A, N));
}
}
|
Javascript
<script>
function getMax(A, N)
{
var B = new Array(N+2);
B[0] = 1;
B[N + 1] = 1;
for ( var i = 1; i <= N; i++)
B[i] = A[i - 1];
var dp = new Array(N + 2);
for ( var i = 0; i < dp.length; i++) {
dp[i] = new Array(N + 2).fill(0);
}
for ( var length = 1; length < N + 1; length++)
{
for ( var left = 1; left < N - length + 2; left++)
{
var right = left + length - 1;
for ( var last = left; last < right + 1; last++)
{
dp[left][right] = Math.max(dp[left][right],
dp[left][last - 1] +
B[left - 1] * B[last] * B[right + 1] +
dp[last + 1][right]);
}
}
}
return dp[1][N];
}
var A = [ 1, 2, 3, 4, 5 ];
var N = A.length;
document.write(getMax(A, N));
</script>
|
Time Complexity: O(N3)
Auxiliary Space: O(N2)
Please Login to comment...