Created
December 22, 2011 12:06
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Code that traverses a matrix in spiral using recursion and a simple state machine.
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public class SpiralMatrix { | |
enum Direction { | |
LEFT_RIGHT, TOP_DOWN, RIGHT_LEFT, BOTTOM_UP | |
}; | |
public static void traverseMatrixInSpiral(char[][] matrix, int initialRow, | |
int finalRow, int initialColumn, int finalColumn, int totalElems, | |
int visited, Direction direction) { | |
System.out.println("Num Elems: " + totalElems + " visited: " + visited); | |
if (visited != totalElems) { | |
int count = 0; | |
switch (direction) { | |
case LEFT_RIGHT: | |
for (int col = initialColumn; col <= finalColumn; col++) { | |
System.out.print(matrix[initialRow][col] + " "); | |
count++; | |
} | |
traverseMatrixInSpiral(matrix, initialRow + 1, finalRow, | |
initialColumn, finalColumn, totalElems, | |
visited + count, Direction.TOP_DOWN); | |
break; | |
case TOP_DOWN: | |
for (int row = initialRow; row <= finalRow; row++) { | |
System.out.print(matrix[row][finalColumn] + " "); | |
count++; | |
} | |
traverseMatrixInSpiral(matrix, initialRow, finalRow, | |
initialColumn, finalColumn - 1, totalElems, visited | |
+ count, Direction.RIGHT_LEFT); | |
break; | |
case RIGHT_LEFT: | |
for (int col = finalColumn; col >= initialColumn; col--) { | |
System.out.print(matrix[finalRow][col] + " "); | |
count++; | |
} | |
traverseMatrixInSpiral(matrix, initialRow, finalRow - 1, | |
initialColumn, finalColumn, totalElems, | |
visited + count, Direction.BOTTOM_UP); | |
break; | |
case BOTTOM_UP: | |
for (int row = finalRow; row >= initialRow; row--) { | |
System.out.print(matrix[row][initialColumn] + " "); | |
count++; | |
} | |
traverseMatrixInSpiral(matrix, initialRow, finalRow, | |
initialColumn + 1, finalColumn, totalElems, visited | |
+ count, Direction.LEFT_RIGHT); | |
break; | |
} | |
} | |
} | |
/** | |
* Create the matrix and call the recursive call to traverse the matrix in | |
* spiral | |
*/ | |
public static void main(String[] args) { | |
char[][] matrix = new char[][] { { 'a', 'b', 'c' }, { 'h', 'i', 'd' }, | |
{ 'g', 'f', 'e' } }; | |
int lastRow = matrix.length - 1; | |
int lastColumn = matrix[0].length - 1; | |
int totalElems = matrix.length * matrix[0].length; | |
traverseMatrixInSpiral(matrix, 0, lastRow, 0, lastColumn, totalElems, | |
0, Direction.LEFT_RIGHT); | |
} | |
} |
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