x
No Plagiarism!6aUAXh52dLNzWRyyTcUwposted on PENANA Q: You have a 2-D grid of size m x n representing a box, and you have n balls. The box is open on the top and bottom sides.8964 copyright protection418PENANAOoMZrqoTBa 維尼
Each cell in the box has a diagonal board spanning two corners of the cell that can redirect a ball to the right or to the left.8964 copyright protection418PENANAnkDn2ydnBn 維尼
- A board that redirects the ball to the right spans the top-left corner to the bottom-right corner and is represented in the grid as 1.
- A board that redirects the ball to the left spans the top-right corner to the bottom-left corner and is represented in the grid as -1.
We drop one ball at the top of each column of the box. Each ball can get stuck in the box or fall out of the bottom. A ball gets stuck if it hits a "V" shaped pattern between two boards or if a board redirects the ball into either wall of the box.8964 copyright protection418PENANADlVQMw72De 維尼
Return an array answer of size n where answer[i] is the column that the ball falls out of at the bottom after dropping the ball from the ith column at the top, or -1 if the ball gets stuck in the box.8964 copyright protection418PENANAfPUc2unXQC 維尼
* [grid[0].length] = column number8964 copyright protection418PENANAotXA4oWQHU 維尼
A: 8964 copyright protection418PENANAJZuILpTTYF 維尼
1. Depth First Search (DFS): 8964 copyright protection418PENANAWqRBHaJPWf 維尼
Condition 1: The ball reaches a point where it can no longer move ahead. In this case, we will return -1. Condition 2: The ball reaches the last row. In this case, we will return the column in which the ball will drop.8964 copyright protection418PENANA5GCkfoxyAR 維尼
*Using Recursive function8964 copyright protection418PENANAvYAqdXkefn 維尼
class Solution {8964 copyright protection418PENANAjWaWemjkfB 維尼
public int[] findBall(int[][] grid) {8964 copyright protection418PENANA6zlTIQn9T8 維尼
// create new int[], for int[grid[0].length]8964 copyright protection418PENANALJoeReSuBv 維尼
int result[] = new int[grid[0].length];8964 copyright protection418PENANA82cPNfAgMF 維尼
// how many ball as well as how many row8964 copyright protection418PENANALX6Om23Xpg 維尼
for (int i = 0; i < grid[0].length; i++) {8964 copyright protection418PENANAbumXBqMoKe 維尼
result[i] = findBallDropColumn(0, i, grid);8964 copyright protection418PENANAnOxz52cjDD 維尼
}8964 copyright protection418PENANAC1PqwLjNOr 維尼
return result;8964 copyright protection418PENANAuxsAYd3ZZq 維尼
}8964 copyright protection418PENANABfZdI9Olv5 維尼
public int findBallDropColumn(int row, int col, int[][] grid) {8964 copyright protection418PENANAE6jEsdI7sF 維尼
// base case; ball reached the last row8964 copyright protection418PENANANlfyfaJ98o 維尼
if (row == grid.length)8964 copyright protection418PENANAzcyUnKSBBK 維尼
return col;8964 copyright protection418PENANACiNI5fKBkF 維尼
int nextColumn = col + grid[row][col];8964 copyright protection418PENANAYtDzNcLwPf 維尼
if (nextColumn < 0 ||8964 copyright protection418PENANAkpx7QnyLdv 維尼
nextColumn > grid[0].length - 1 ||8964 copyright protection418PENANAMHKkpeCUMf 維尼
// [1,1] & [-1,-1]drop, [1,-1] & [-1,1] stuck8964 copyright protection418PENANArzVkjGNFky 維尼
grid[row][col] != grid[row][nextColumn]) {8964 copyright protection418PENANAkbZOg2Anfe 維尼
return -1;8964 copyright protection418PENANAW0iKpOcgl5 維尼
}8964 copyright protection418PENANAdgwVztRKLb 維尼
return findBallDropColumn(row + 1, nextColumn, grid);8964 copyright protection418PENANAEMMrLcE6Am 維尼
}8964 copyright protection418PENANAKvJpZjxrEp 維尼
}8964 copyright protection418PENANAgdwBZgVwYZ 維尼
2. Dynamic Programming Approach:8964 copyright protection418PENANAkhF52MQV9F 維尼
class Solution {8964 copyright protection418PENANAP303Q2bEuF 維尼
public int[] findBall(int[][] grid) {8964 copyright protection418PENANAtJkPGl0K6O 維尼
int result[] = new int[grid[0].length];8964 copyright protection418PENANAW5JYQAOIF4 維尼
Integer memo[][] = new Integer[grid.length + 1][grid[0].length];422Please respect copyright.PENANA58Dd2SBQjT
8964 copyright protection418PENANATrutPosYZ9 維尼
422Please respect copyright.PENANAh7L63vWA4U
8964 copyright protection418PENANA4SQoiDBOw5 維尼
for (int row = grid.length; row >= 0; row--) {8964 copyright protection418PENANAieaKtVecCW 維尼
for (int col = 0; col < grid[0].length; col++) {8964 copyright protection418PENANAu4khz40woe 維尼
if (row == grid.length) {8964 copyright protection418PENANALPhQPxTN1v 維尼
// for the last row 422Please respect copyright.PENANAOit11CKICm
8964 copyright protection418PENANAGSXjxr3SMR 維尼
memo[row][col] = col;8964 copyright protection418PENANA3TDRS4bhkD 維尼
continue;8964 copyright protection418PENANAEHrJPmkRFk 維尼
}8964 copyright protection418PENANAfK9Wu3QA9U 維尼
// for the remaining row.8964 copyright protection418PENANAPw7otuSTyn 維尼
int nextColumn = col + grid[row][col];8964 copyright protection418PENANAza32j8aOos 維尼
if (nextColumn < 0 ||8964 copyright protection418PENANAFRlc51EXWg 維尼
nextColumn > grid[0].length - 1 ||8964 copyright protection418PENANAVAWoat53PL 維尼
grid[row][col] != grid[row][nextColumn])8964 copyright protection418PENANAOVDD58zVlC 維尼
memo[row][col] = -1;8964 copyright protection418PENANA6qR5Nz9QDP 維尼
else8964 copyright protection418PENANAJea6X8TPB0 維尼
memo[row][col] = memo[row + 1][nextColumn];8964 copyright protection418PENANAspxF1aYW7d 維尼
// reaching row 0, copy the values in all the column in the result array. 422Please respect copyright.PENANAfuAOVl0A2f
8964 copyright protection418PENANA8Xtjn2AEQ8 維尼
if (row == 0) {8964 copyright protection418PENANALd121jpPBA 維尼
result[col] = memo[row][col];8964 copyright protection418PENANABf4j0GPF80 維尼
}8964 copyright protection418PENANAJ206ul1Dub 維尼
}8964 copyright protection418PENANAW43DkfZ4Pi 維尼
}8964 copyright protection418PENANAlLMt1mLkGI 維尼
return result;8964 copyright protection418PENANAQLRoBSP5pY 維尼
}8964 copyright protection418PENANAkZYZHx1pLp 維尼
}8964 copyright protection418PENANAZGbbPr0opG 維尼
3. Iterative Approach, Simulation:8964 copyright protection418PENANAPcouutHC7R 維尼
class Solution {8964 copyright protection418PENANAAlDBcvaJgH 維尼
public int[] findBall(int[][] grid) {8964 copyright protection418PENANALSYukBJdCG 維尼
int result[] = new int[grid[0].length];8964 copyright protection418PENANA5SpvR9zSUD 維尼
// 1. Start by picking up a ball starting from every column col, iterating from the 0th column to the last column. Initialize the current column as col.8964 copyright protection418PENANAcy2dXOZkw5 維尼
for (int col = 0; col < grid[0].length; col++) {8964 copyright protection418PENANAfTLNzXHT4P 維尼
int currentCol = col;8964 copyright protection418PENANANy9nMqVP2s 維尼
// 2. For every such ball, simulate its movement in every row ranging from the 0th to the nth row.8964 copyright protection418PENANAF3vtP2vckU 維尼
for (int row = 0; row < grid.length; row++) {8964 copyright protection418PENANApL8Glg2avl 維尼
int nextColumn = currentCol + grid[row][currentCol];8964 copyright protection418PENANAjWRTRCH2kx 維尼
// stuck case 8964 copyright protection418PENANAAiRa0KUrW5 維尼
if (nextColumn < 0 ||8964 copyright protection418PENANAUDWn3SEV50 維尼
nextColumn > grid[0].length - 1 ||8964 copyright protection418PENANAC5NY8T9yng 維尼
grid[row][currentCol] != grid[row][nextColumn]) {8964 copyright protection418PENANAHloaguh6H1 維尼
result[col] = -1;8964 copyright protection418PENANAcZyEiJFTAb 維尼
break;8964 copyright protection418PENANA6fEcLgfbIx 維尼
}8964 copyright protection418PENANATRoZsJDMYa 維尼
// 3. Update the value of nextColumn in the result array for every row. In the end, the result will store the column number where the ball will fall after the last row. (result[col] = currentCol, return the result)8964 copyright protection418PENANAcn7eP5dkc8 維尼
result[col] = nextColumn;8964 copyright protection418PENANAxJbqy6rv7z 維尼
currentCol = nextColumn;8964 copyright protection418PENANAmpe1Vbp1vu 維尼
}8964 copyright protection418PENANA7qnpQIDxj6 維尼
}8964 copyright protection418PENANAgs1JWqZpPQ 維尼
return result;8964 copyright protection418PENANAhARvczSzKl 維尼
}8964 copyright protection418PENANA3owYogtdeV 維尼
}8964 copyright protection418PENANAQ56vQwUMwq 維尼
216.73.216.41
ns216.73.216.41da2