SpiralMatrix.java

publicclassSolution {
publicList<Integer> spiralOrder(int[][] matrix) {

List<Integer> res = newArrayList<Integer>();

if (matrix.length == 0) {
returnres;
 }

introwBegin = 0;
introwEnd = matrix.length-1;
intcolBegin = 0;
intcolEnd = matrix[0].length - 1;

while (rowBegin <= rowEnd && colBegin <= colEnd) {
// Traverse Right
for (intj = colBegin; j <= colEnd; j ++) {
res.add(matrix[rowBegin][j]);
 }
rowBegin++;

// Traverse Down
for (intj = rowBegin; j <= rowEnd; j ++) {
res.add(matrix[j][colEnd]);
 }
colEnd--;

if (rowBegin <= rowEnd) {
// Traverse Left
for (intj = colEnd; j >= colBegin; j --) {
res.add(matrix[rowEnd][j]);
 }
 }
rowEnd--;

if (colBegin <= colEnd) {
// Traver Up
for (intj = rowEnd; j >= rowBegin; j --) {
res.add(matrix[j][colBegin]);
 }
 }
colBegin ++;
 }

returnres;
 }
}