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Code01_MinPathSum.java
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Code01_MinPathSum.java
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package class21;
public class Code01_MinPathSum {
public static int minPathSum1(int[][] m) {
if (m == null || m.length == 0 || m[0] == null || m[0].length == 0) {
return 0;
}
int row = m.length;
int col = m[0].length;
int[][] dp = new int[row][col];
dp[0][0] = m[0][0];
for (int i = 1; i < row; i++) {
dp[i][0] = dp[i - 1][0] + m[i][0];
}
for (int j = 1; j < col; j++) {
dp[0][j] = dp[0][j - 1] + m[0][j];
}
for (int i = 1; i < row; i++) {
for (int j = 1; j < col; j++) {
dp[i][j] = Math.min(dp[i - 1][j], dp[i][j - 1]) + m[i][j];
}
}
return dp[row - 1][col - 1];
}
public static int minPathSum2(int[][] m) {
if (m == null || m.length == 0 || m[0] == null || m[0].length == 0) {
return 0;
}
int row = m.length;
int col = m[0].length;
int[] dp = new int[col];
dp[0] = m[0][0];
for (int j = 1; j < col; j++) {
dp[j] = dp[j - 1] + m[0][j];
}
for (int i = 1; i < row; i++) {
dp[0] += m[i][0];
for (int j = 1; j < col; j++) {
dp[j] = Math.min(dp[j - 1], dp[j]) + m[i][j];
}
}
return dp[col - 1];
}
// for test
public static int[][] generateRandomMatrix(int rowSize, int colSize) {
if (rowSize < 0 || colSize < 0) {
return null;
}
int[][] result = new int[rowSize][colSize];
for (int i = 0; i != result.length; i++) {
for (int j = 0; j != result[0].length; j++) {
result[i][j] = (int) (Math.random() * 100);
}
}
return result;
}
// for test
public static void printMatrix(int[][] matrix) {
for (int i = 0; i != matrix.length; i++) {
for (int j = 0; j != matrix[0].length; j++) {
System.out.print(matrix[i][j] + " ");
}
System.out.println();
}
}
public static void main(String[] args) {
int rowSize = 10;
int colSize = 10;
int[][] m = generateRandomMatrix(rowSize, colSize);
System.out.println(minPathSum1(m));
System.out.println(minPathSum2(m));
}
}