题目:
地上有个m行n列的方格。一个机器人从坐标(0,0)的格子开始移动,它每一次可以向左、右、上、下移动一格,但不能进入行坐标和列坐标的数位之和大于k的格子。
例如,当k为18时,机器人能够进入方格(35,37),因为3+5+3+7=18.但它不能进入方格(35,38),因为3+5+3+8=19.请问该机器人能够达到多少格子?
和上一题66 - 矩阵中的路径类似,只是约束条件发生了改变。
当机器人在某一个格子时,它能够向上下左右四个方向运动,当访问周围的格子时,标记为已访问,判断该格子坐标是否满足要求,满足则计数加 1,否则计数加 0. 当遍历完所有格子时,计数完毕。
bool CheckNum(int row, int col, int threshold); // 检查坐标是否满足要求
int MoveCountsCore(int rows, int cols, int row, int col, bool* visited, int threshold);
int MoveCounts(int threshold, int rows, int cols) {
if (rows < || cols < || threshold < ) {
return ;
}
bool* visited = new bool [rows*cols]; //访问记录
for (int i = ; i < rows*cols; i++)
visited[i] = false;
int counts = MoveCountsCore(rows, cols, , , visited, threshold);
delete []visited;
return counts;
}
int MoveCountsCore(int rows, int cols, int row, int col, bool* visited, int threshold) {
if (rows < || cols < || row < || col < || threshold < )
return ;
if (row < rows && col < cols && !visited[row*cols + col] && CheckNum(row, col, threshold)) {
visited[row*cols + col] = true;
return + MoveCountsCore(rows, cols, row-, col, visited, threshold) +
MoveCountsCore(rows, cols, row, col-, visited, threshold) +
MoveCountsCore(rows, cols, row+, col, visited, threshold) +
MoveCountsCore(rows, cols, row, col+, visited, threshold);
}
return ;
}
// 检查坐标是否,满足要求
bool CheckNum(int row, int col, int threshold) {
if (row < || col < || threshold< )
return false;
int bit_sum = ;
while (row != ) {
bit_sum += row % ;
row /= ;
}
while (col != ) {
bit_sum += col % ;
col /= ;
}
if (bit_sum <= threshold)
return true;
else
return false;
}
测试样例:
From 《剑指offer》 GitHub
// ================================ test code ================================
void test(char* testName, int threshold, int rows, int cols, int expected)
{
if(testName != NULL)
printf("%s begins: ", testName);
if(MoveCounts(threshold, rows, cols) == expected)
printf("Passed.\n");
else
printf("FAILED.\n");
}
void test1()
{
test("Test1", , , , );
}
void test2()
{
test("Test2", , , , );
}
void test3()
{
test("Test3", , , , );
}
void test4()
{
test("Test4", , , , );
}
void test5()
{
test("Test5", , , , );
}
void test6()
{
test("Test6", , , , );
}
void test7()
{
test("Test7", , , , );
}
void test8()
{
test("Test8", -, , , );
}
int main(int agrc, char* argv[])
{
test1();
test2();
test3();
test4();
test5();
test6();
test7();
test8();
}