x
No Plagiarism!SzQxrqEtif1ZKIFn1Yrwposted 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 protection411PENANAsvLCrlmocr 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 protection411PENANAsG6W3YOL9n 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 protection411PENANA0lwWLR7NG7 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 protection411PENANAnTmKyzXNVc 維尼
* [grid[0].length] = column number8964 copyright protection411PENANAIOAxdpC6FT 維尼
A: 8964 copyright protection411PENANAoX3t4bsAZn 維尼
1. Depth First Search (DFS): 8964 copyright protection411PENANA0khHSMCcPn 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 protection411PENANAXyuPbGt1vX 維尼
*Using Recursive function8964 copyright protection411PENANAuIaxd7QkXV 維尼
class Solution {8964 copyright protection411PENANAYdLGOxm1HM 維尼
public int[] findBall(int[][] grid) {8964 copyright protection411PENANARRNj4gkztm 維尼
// create new int[], for int[grid[0].length]8964 copyright protection411PENANACrTsQGdTfu 維尼
int result[] = new int[grid[0].length];8964 copyright protection411PENANAgz6fiTCB3J 維尼
// how many ball as well as how many row8964 copyright protection411PENANAWfrlSuS3n6 維尼
for (int i = 0; i < grid[0].length; i++) {8964 copyright protection411PENANAgqcTtTFQ7H 維尼
result[i] = findBallDropColumn(0, i, grid);8964 copyright protection411PENANAE060CeFmr3 維尼
}8964 copyright protection411PENANA8763Q5AOFb 維尼
return result;8964 copyright protection411PENANAcrHhjJhOEe 維尼
}8964 copyright protection411PENANAbesh2TLnwU 維尼
public int findBallDropColumn(int row, int col, int[][] grid) {8964 copyright protection411PENANAPERQfBjk9U 維尼
// base case; ball reached the last row8964 copyright protection411PENANAAFBAdXLL3e 維尼
if (row == grid.length)8964 copyright protection411PENANAVs0gMPAkt5 維尼
return col;8964 copyright protection411PENANA0LBpUTdZdw 維尼
int nextColumn = col + grid[row][col];8964 copyright protection411PENANANdusS4VNrP 維尼
if (nextColumn < 0 ||8964 copyright protection411PENANAaB3bkKF86q 維尼
nextColumn > grid[0].length - 1 ||8964 copyright protection411PENANApXhblsMkqy 維尼
// [1,1] & [-1,-1]drop, [1,-1] & [-1,1] stuck8964 copyright protection411PENANApMRjOwsYvB 維尼
grid[row][col] != grid[row][nextColumn]) {8964 copyright protection411PENANAOhwz8LQuNU 維尼
return -1;8964 copyright protection411PENANAo6YllL2x5S 維尼
}8964 copyright protection411PENANA1D7zbJCjxY 維尼
return findBallDropColumn(row + 1, nextColumn, grid);8964 copyright protection411PENANAlbnYKTfs5W 維尼
}8964 copyright protection411PENANAka6cS1SamT 維尼
}8964 copyright protection411PENANAx5F2xtXvnW 維尼
2. Dynamic Programming Approach:8964 copyright protection411PENANAT44YjG4wxa 維尼
class Solution {8964 copyright protection411PENANAm0jgjejZdj 維尼
public int[] findBall(int[][] grid) {8964 copyright protection411PENANAK3nlTVEGxY 維尼
int result[] = new int[grid[0].length];8964 copyright protection411PENANAnE2qF4Q3Md 維尼
Integer memo[][] = new Integer[grid.length + 1][grid[0].length];415Please respect copyright.PENANAilcg3AoqHF
8964 copyright protection411PENANACsA3e4Ojzq 維尼
415Please respect copyright.PENANACFynbqUMaU
8964 copyright protection411PENANAQflu4U6HjE 維尼
for (int row = grid.length; row >= 0; row--) {8964 copyright protection411PENANAGdC116FEr9 維尼
for (int col = 0; col < grid[0].length; col++) {8964 copyright protection411PENANAlxsJbGYGMY 維尼
if (row == grid.length) {8964 copyright protection411PENANAZxLl95C9ft 維尼
// for the last row 415Please respect copyright.PENANA6UiLzutVJb
8964 copyright protection411PENANA26twAXt6B5 維尼
memo[row][col] = col;8964 copyright protection411PENANALUS9QM32R9 維尼
continue;8964 copyright protection411PENANAK5S9lvtC06 維尼
}8964 copyright protection411PENANAkEFPg3mttk 維尼
// for the remaining row.8964 copyright protection411PENANA22lFgrNPkR 維尼
int nextColumn = col + grid[row][col];8964 copyright protection411PENANAt0nnuAFslI 維尼
if (nextColumn < 0 ||8964 copyright protection411PENANAgHJTHZrpI0 維尼
nextColumn > grid[0].length - 1 ||8964 copyright protection411PENANAr86HPyJse1 維尼
grid[row][col] != grid[row][nextColumn])8964 copyright protection411PENANAcsH1YbKQLj 維尼
memo[row][col] = -1;8964 copyright protection411PENANAZCH3IwwJzo 維尼
else8964 copyright protection411PENANAPkRsG5awBO 維尼
memo[row][col] = memo[row + 1][nextColumn];8964 copyright protection411PENANAN0FZGH9LFf 維尼
// reaching row 0, copy the values in all the column in the result array. 415Please respect copyright.PENANAQjNto2hxr8
8964 copyright protection411PENANA6P06LsEX4V 維尼
if (row == 0) {8964 copyright protection411PENANANcFZiZ6bjj 維尼
result[col] = memo[row][col];8964 copyright protection411PENANAAjYcQG6SYT 維尼
}8964 copyright protection411PENANAhOkhsij40Q 維尼
}8964 copyright protection411PENANApeskOJJ9r8 維尼
}8964 copyright protection411PENANAPYlQmwD9wD 維尼
return result;8964 copyright protection411PENANAi6shBDKK7C 維尼
}8964 copyright protection411PENANAawVcoJdoV0 維尼
}8964 copyright protection411PENANAg5LEK1vYli 維尼
3. Iterative Approach, Simulation:8964 copyright protection411PENANAaZgDaneX5A 維尼
class Solution {8964 copyright protection411PENANAbuCUM4rttN 維尼
public int[] findBall(int[][] grid) {8964 copyright protection411PENANAntgNVCqv3T 維尼
int result[] = new int[grid[0].length];8964 copyright protection411PENANAm85f7WLzoM 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 protection411PENANANkYV8gYY4x 維尼
for (int col = 0; col < grid[0].length; col++) {8964 copyright protection411PENANAIJK5lFcpb2 維尼
int currentCol = col;8964 copyright protection411PENANA1vk2yGsAlN 維尼
// 2. For every such ball, simulate its movement in every row ranging from the 0th to the nth row.8964 copyright protection411PENANAVTmUVg2W48 維尼
for (int row = 0; row < grid.length; row++) {8964 copyright protection411PENANA4UgHZEt8Kt 維尼
int nextColumn = currentCol + grid[row][currentCol];8964 copyright protection411PENANAyHrF82PBlj 維尼
// stuck case 8964 copyright protection411PENANAgBnWovEo2Y 維尼
if (nextColumn < 0 ||8964 copyright protection411PENANA1DqERn6YMc 維尼
nextColumn > grid[0].length - 1 ||8964 copyright protection411PENANAVHVSA4GznQ 維尼
grid[row][currentCol] != grid[row][nextColumn]) {8964 copyright protection411PENANAzJrlgINxJm 維尼
result[col] = -1;8964 copyright protection411PENANAX5zGocwz27 維尼
break;8964 copyright protection411PENANAR3igjvCTiV 維尼
}8964 copyright protection411PENANA3vi5ecLEve 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 protection411PENANAuvNPKNKZxx 維尼
result[col] = nextColumn;8964 copyright protection411PENANAWKzl4x1WL5 維尼
currentCol = nextColumn;8964 copyright protection411PENANAebFuMd7PZA 維尼
}8964 copyright protection411PENANA1v0dvXXMZk 維尼
}8964 copyright protection411PENANAHIUDgBkYHQ 維尼
return result;8964 copyright protection411PENANA26Yby5CMjS 維尼
}8964 copyright protection411PENANACzAaGnwrUN 維尼
}8964 copyright protection411PENANA6bHwxjTNdK 維尼
216.73.216.210
ns216.73.216.210da2