本文是一道2015 Google校招在线测试题题目是关于2048游戏的，感兴趣的同学参考下。

先附代码：（简单地说就是给出一个矩阵代表2048游戏的一个状态以及一个方向，输出往这个方向移动之后的矩阵）

#include
#include
#include
using namespace std;
int main()
{
int T;
ifstream ifile("B-large-practice.in");
ofstream ofile("out1.txt");
int num[21][21];
ifile >> T;
for(int n_case = 1; n_case <= T; n_case++)
{
for(int i = 0; i < 21; i++)
for(int j = 0; j < 21; j++)
num[i][j] = 0;
int n;
string flag;
ifile >> n;
ifile >> flag;
for(int i = 0; i < n; i++)
for(int j = 0; j < n; j++)
ifile >> num[i][j];
if(flag == "up")
{
for(int j = 0; j < n; j++)
{
for(int i = 0; i < n; i++)
{
if(num[i][j] != 0)
{
int tmp_i = i;
while(num[++i][j] == 0)
{;}
if(i < n && num[tmp_i][j] == num[i][j])
{
num[tmp_i][j] = num[tmp_i][j] * 2;
num[i][j] = 0;
}
i--;
}
}
}
for(int j = 0; j < n; j++)
{
int index = 0;
for(int i = 0; i < n; i++)
if(num[i][j] != 0)
{
int tmp = num[index][j];
num[index][j] = num[i][j];
num[i][j] = tmp;
index++;
}
}
ofile << "Case #" << n_case << ":\n";
for(int i = 0; i < n; i++)
{
for(int j = 0; j < n; j++)
{
ofile << num[i][j];
if(j != n - 1)
ofile << ' ';
}
ofile << endl;
}
}
else if(flag == "down")
{
for(int j = 0; j < n; j++)
{
for(int i = n - 1; i > -1; i--)
{
if(num[i][j] != 0)
{
int tmp_i = i;
while(num[--i][j] == 0)
{}
if(i >= 0 && num[tmp_i][j] == num[i][j])
{
num[tmp_i][j] = num[tmp_i][j] * 2;
num[i][j] = 0;
}
i++;
}
}
}
for(int j = 0; j < n; j++)
{
int index = n - 1;
for(int i = n - 1; i >= 0; i--)
if(num[i][j] != 0)
{
int tmp = num[index][j];
num[index][j] = num[i][j];
num[i][j] = tmp;
index--;
}
}
ofile << "Case #" << n_case << ":\n";
for(int i = 0; i < n; i++)
{
for(int j = 0; j < n; j++)
{
ofile << num[i][j];
if(j != n - 1)
ofile << ' ';
}
ofile << endl;
}
}
else if(flag == "left")
{
for(int i = 0; i < n; i++)
{
for(int j = 0; j < n; j++)
{
if(num[i][j] != 0)
{
int tmp_j = j;
while(num[i][++j] == 0)
{}
if(j < n && num[i][tmp_j] == num[i][j])
{
num[i][tmp_j] = num[i][tmp_j] * 2;
num[i][j] = 0;
}
j--;
}
}
}
for(int i = 0; i < n; i++)
{
int index = 0;
for(int j = 0; j < n; j++)
if(num[i][j] != 0)
{
int tmp = num[i][index];
num[i][index] = num[i][j];
num[i][j] = tmp;
index++;
}
}
ofile << "Case #" << n_case << ":\n";
for(int i = 0; i < n; i++)
{
for(int j = 0; j < n; j++)
{
ofile << num[i][j];
if(j != n - 1)
ofile << ' ';
}
ofile << endl;
}
}
else
{
for(int i = 0; i < n; i++)
{
for(int j = n - 1; j >= 0; j--)
{
if(num[i][j] != 0)
{
int tmp_j = j;
while(num[i][--j] == 0)
{}
if(j >= 0 && num[i][tmp_j] == num[i][j])
{
num[i][tmp_j] = num[i][tmp_j] * 2;
num[i][j] = 0;
}
j++;
}
}
}
for(int i = 0; i < n; i++)
{
int index = n - 1;
for(int j = n - 1; j >= 0; j--)
if(num[i][j] != 0)
{
int tmp = num[i][index];
num[i][index] = num[i][j];
num[i][j] = tmp;
index--;
}
}
ofile << "Case #" << n_case << ":\n";
for(int i = 0; i < n; i++)
{
for(int j = 0; j < n; j++)
{
ofile << num[i][j];
if(j != n - 1)
ofile << ' ';
}
ofile << endl;
}
}
}
}

2048 is a famous single-player game in which the objective is to slide tiles on a grid to combine them and create a tile with the number 2048.

2048 is played on a simple 4 x 4 grid with tiles that slide smoothly when a player moves them. For each movement, the player can choose to move all tiles in 4 directions, left, right, up, and down, as far as possible at the same time. If two tiles of the same number collide while moving, they will merge into a tile with the total value of the two tiles that collided. In one movement, one newly created tile can not be merged again and always is merged with the tile next to it along the moving direction first. E.g. if the three "2" are in a row "2 2 2" and the player choose to move left, it will become "4 2 0", the most left 2 "2" are merged.

The above figure shows how 4 x 4 grid varies when player moves all tiles 'right'.