BoxStackingProblem.cpp

#include<stdio.h> 
#include<stdlib.h> 

struct Box 
{ 
int h, w, d; 
}; 

int min (int x, int y) 
{ return (x < y)? x : y; } 

int max (int x, int y) 
{ return (x > y)? x : y; } 

int compare (const void *a, const void * b) 
{ 
	return ( (*(Box *)b).d * (*(Box *)b).w ) - 
		( (*(Box *)a).d * (*(Box *)a).w ); 
} 

int maxStackHeight( Box arr[], int n ) 
{ 
Box rot[3*n]; 
int index = 0; 
for (int i = 0; i < n; i++) 
{ 
	rot[index].h = arr[i].h; 
	rot[index].d = max(arr[i].d, arr[i].w); 
	rot[index].w = min(arr[i].d, arr[i].w); 
	index++; 

	rot[index].h = arr[i].w; 
	rot[index].d = max(arr[i].h, arr[i].d); 
	rot[index].w = min(arr[i].h, arr[i].d); 
	index++; 

	rot[index].h = arr[i].d; 
	rot[index].d = max(arr[i].h, arr[i].w); 
	rot[index].w = min(arr[i].h, arr[i].w); 
	index++; 
} 

n = 3*n; 

qsort (rot, n, sizeof(rot[0]), compare); 

int msh[n]; 
for (int i = 0; i < n; i++ ) 
	msh[i] = rot[i].h; 

for (int i = 1; i < n; i++ ) 
	for (int j = 0; j < i; j++ ) 
		if ( rot[i].w < rot[j].w && 
			rot[i].d < rot[j].d && 
			msh[i] < msh[j] + rot[i].h 
			) 
		{ 
			msh[i] = msh[j] + rot[i].h; 
		} 


int max = -1; 
for ( int i = 0; i < n; i++ ) 
	if ( max < msh[i] ) 
		max = msh[i]; 

return max; 
} 

int main() 
{ 
Box arr[] = { {4, 6, 7}, {1, 2, 3}, {4, 5, 6}, {10, 12, 32} }; 
int n = sizeof(arr)/sizeof(arr[0]); 

printf("The maximum possible height of stack is %d\n", 
		maxStackHeight (arr, n) ); 

return 0; 
}