題目描述
地上有一個m行和n列的方格。一個機器人從坐标0,0的格子開始移動,每一次隻能向左,右,上,下四個方向移動一格,但是不能進入行坐标和列坐标的數位之和大于k的格子。
例如,當k為18時,機器人能夠進入方格(35,37),因為3+5+3+7 = 18。但是,它不能進入方格(35,38),因為3+5+3+8
= 19。請問該機器人能夠達到多少個格子?
public class Solution
public int movingCount(int threshold, int rows, int cols) {
boolean[] visited = new boolean[rows * cols];
return movingCountCore(threshold, rows, cols, 0, 0, visited);
}
public int movingCountCore(int threshold, int rows, int cols,
int row, int col, boolean[] visited) {
int count = 0;
// 檢查能否進入方格
if(check(threshold, rows, cols, row, col, visited)) {
visited[row * cols + col] = true;
count = 1 + movingCountCore(threshold, rows, cols, row - 1, col, visited)
+ movingCountCore(threshold, rows, cols, row + 1, col, visited)
+ movingCountCore(threshold, rows, cols, row, col - 1, visited)
+ movingCountCore(threshold, rows, cols, row, col + 1, visited);
}
return count;
}
public boolean check(int threshold, int rows, int cols,
int row, int col, boolean[] visited) {
return (row >=0
&& row < rows
&& col >=0
&& col < cols
&& (!visited[row * cols + col])
&& (getDigitSum(row) + getDigitSum(col) <= threshold)
);
}
public int getDigitSum(int n) {
int sum = 0;
while(n > 0) {
sum += n % 10;
n = n / 10;
}
return