Un par de buenos técnicamente respuestas aquí ya, pero aquí está una manera más visual de entenderlo ...
OK, para que sepa cómo pasar del caso unidimensional al caso bidimensional.
Una matriz 1-D se parece a esto:
int [5] :
+-----+-----+-----+-----+-----+
| 0 | 1 | 2 | 3 | 4 |
| | | | | |
+-----+-----+-----+-----+-----+
Y una matriz 2-D se parece a esto:
int [5][5] :
+-----+-----+-----+-----+-----+
| 0,0 | 0,1 | 0,2 | 0,3 | 0,4 |
| | | | | |
+-----+-----+-----+-----+-----+
| 1,0 | 1,1 | 1,2 | 1,3 | 1,4 |
| | | | | |
+-----+-----+-----+-----+-----+
| 2,0 | 2,1 | 2,2 | 2,3 | 2,4 |
| | | | | |
+-----+-----+-----+-----+-----+
| 3,0 | 3,1 | 3,2 | 3,3 | 3,4 |
| | | | | |
+-----+-----+-----+-----+-----+
| 4,0 | 4,1 | 4,2 | 4,3 | 4,4 |
| | | | | |
+-----+-----+-----+-----+-----+
Usted podía imagen de la conversión a la correspondiente 1-D matriz como esta:
+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+- - -
| 0,0 | 0,1 | 0,2 | 0,3 | 0,4 | 1,0 | 1,1 | 1,2 | 1,3 | 1,4 | etc.
| | | | | | | | | | |
+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+- - -
vvv
+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+- - -
| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | etc.
| | | | | | | | | | |
+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+- - -
Pero una forma alternativa de pensar una pelea es de imaginar la matriz original, pero re-etiquetados - como esto:
int [5][5] :
+-----+-----+-----+-----+-----+ +-----+-----+-----+-----+-----+
| 0,0 | 0,1 | 0,2 | 0,3 | 0,4 | | 0 | 1 | 2 | 3 | 4 |
| | | | | | | | | | | |
+-----+-----+-----+-----+-----+ +-----+-----+-----+-----+-----+
| 1,0 | 1,1 | 1,2 | 1,3 | 1,4 | | 5 | 6 | 7 | 8 | 9 |
| | | | | | | | | | | |
+-----+-----+-----+-----+-----+ +-----+-----+-----+-----+-----+
| 2,0 | 2,1 | 2,2 | 2,3 | 2,4 | => | 10 | 11 | 12 | 13 | 14 |
| | | | | | | | | | | |
+-----+-----+-----+-----+-----+ +-----+-----+-----+-----+-----+
| 3,0 | 3,1 | 3,2 | 3,3 | 3,4 | | 15 | 16 | 17 | 18 | 19 |
| | | | | | | | | | | |
+-----+-----+-----+-----+-----+ +-----+-----+-----+-----+-----+
| 4,0 | 4,1 | 4,2 | 4,3 | 4,4 | | 20 | 21 | 22 | 23 | 24 |
| | | | | | | | | | | |
+-----+-----+-----+-----+-----+ +-----+-----+-----+-----+-----+
2-D array index [i][j] => 1-D array index [i*5 + j]
... y si se piensa en ello de esta manera, el caso de 3 dimensiones se limita a seguir el mismo principio (y así sucesivamente para dimensiones más altas, ¡cada vez es más difícil de visualizar!):
int [5][5][5] :
+-----+-----+-----+-----+-----+ +-----+-----+-----+-----+-----+
|+-----+-----+-----+-----+-----+ |+-----+-----+-----+-----+-----+
||+-----+-----+-----+-----+-----+ ||+-----+-----+-----+-----+-----+
|||+-----+-----+-----+-----+-----+ |||+-----+-----+-----+-----+-----+
||||1,0,0|1,0,1|1,0,2|1,0,3|1,0,4| |||| 25 | 26 | 27 | 28 | 29 |
|||| +-----+-----+-----+-----+-----+ |||| +-----+-----+-----+-----+-----+
|||+---|0,0,0|0,0,1|0,0,2|0,0,3|0,0,4| |||+---| 0 | 1 | 2 | 3 | 4 |
||||1,1| | | | | | |||| 30| | | | | |
|||| +-----+-----+-----+-----+-----+ |||| +-----+-----+-----+-----+-----+
|||+---|0,1,0|0,1,1|0,1,2|0,1,3|0,1,4| |||+---| 5 | 6 | 7 | 8 | 9 |
||||1,2| | | | | | |||| 35| | | | | |
|||| +-----+-----+-----+-----+-----+ |||| +-----+-----+-----+-----+-----+
|||+---|0,2,0|0,2,1|0,2,2|0,2,3|0,2,4|=>|||+---| 10 | 11 | 12 | 13 | 14 |
||||1,3| | | | | | |||| 40| | | | | |
|||| +-----+-----+-----+-----+-----+ |||| +-----+-----+-----+-----+-----+
+||+---|0,3,0|0,3,1|0,3,2|0,3,3|0,3,4| +||+---| 15 | 16 | 17 | 18 | 19 |
+||1,4| | | | | | +|| 45| | | | | |
+| +-----+-----+-----+-----+-----+ +| +-----+-----+-----+-----+-----+
+---|0,4,0|0,4,1|0,4,2|0,4,3|0,4,4| +---| 20 | 21 | 22 | 23 | 24 |
| | | | | | | | | | | |
+-----+-----+-----+-----+-----+ +-----+-----+-----+-----+-----+
3-D array index [i][j][k] => 1-D array index [i*5*5 + j*5 + k]
arte fresco ASCII. – Anycorn
Gracias! ¡buena manera de ilustrarlo! – user436390
Más detalles para int [dimX] [dimY] [dimZ]: índice de matriz 1-D [i * dimY * dimZ + j * dimZ + k] –