/
053_PrintMatrix.java
175 lines (150 loc) · 3.77 KB
/
053_PrintMatrix.java
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// Coding Interviews: Questions, Analysis & Solutions
// Harry He
public class PrintMatrix {
public static void printMatrixClockwise(int numbers[][]) {
int rows = numbers.length;
int columns = numbers[0].length;
int start = 0;
while(columns > start * 2 && rows > start * 2) {
printRing(numbers, start);
++start;
}
}
private static void printRing(int numbers[][], int start)
{
int rows = numbers.length;
int columns = numbers[0].length;
int endX = columns - 1 - start;
int endY = rows - 1 - start;
// Print a row from left to right
for(int i = start; i <= endX; ++i) {
int number = numbers[start][i];
printNumber(number);
}
// print a column top down
if(start < endY) {
for(int i = start + 1; i <= endY; ++i) {
int number = numbers[i][endX];
printNumber(number);
}
}
// print a row from right to left
if(start < endX && start < endY) {
for(int i = endX - 1; i >= start; --i) {
int number = numbers[endY][i];
printNumber(number);
}
}
// print a column bottom up
if(start < endX && start < endY - 1) {
for(int i = endY - 1; i >= start + 1; --i) {
int number = numbers[i][start];
printNumber(number);
}
}
}
private static void printNumber(int number) {
System.out.print(number);
System.out.print("\t");
}
//================= Test Code =================
private static void test(int columns, int rows)
{
System.out.print("Test Begin: ");
System.out.print(columns);
System.out.print(" columns, ");
System.out.print(rows);
System.out.print(" rows.\n");
if(columns < 1 || rows < 1)
return;
int numbers[][] = new int[rows][];
for(int i = 0; i < rows; ++i) {
numbers[i] = new int[columns];
for(int j = 0; j < columns; ++j) {
numbers[i][j] = i * columns + j + 1;
}
}
printMatrixClockwise(numbers);
System.out.print("\n");
}
public static void main(String[] args) {
/*
1
*/
test(1, 1);
/*
1 2
3 4
*/
test(2, 2);
/*
1 2 3 4
5 6 7 8
9 10 11 12
13 14 15 16
*/
test(4, 4);
/*
1 2 3 4 5
6 7 8 9 10
11 12 13 14 15
16 17 18 19 20
21 22 23 24 25
*/
test(5, 5);
/*
1
2
3
4
5
*/
test(1, 5);
/*
1 2
3 4
5 6
7 8
9 10
*/
test(2, 5);
/*
1 2 3
4 5 6
7 8 9
10 11 12
13 14 15
*/
test(3, 5);
/*
1 2 3 4
5 6 7 8
9 10 11 12
13 14 15 16
17 18 19 20
*/
test(4, 5);
/*
1 2 3 4 5
*/
test(5, 1);
/*
1 2 3 4 5
6 7 8 9 10
*/
test(5, 2);
/*
1 2 3 4 5
6 7 8 9 10
11 12 13 14 15
*/
test(5, 3);
/*
1 2 3 4 5
6 7 8 9 10
11 12 13 14 15
16 17 18 19 20
*/
test(5, 4);
}
}