有人能帮我看一下这道题吗? 不胜感激!

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This topic created in 4458 days ago, the information mentioned may be changed or developed.

Write an algorithm such that if an element in an MxN matrix is 0, its entire row and column is set to 0.

#include <iostream>
using namespace std;

void setZero(int **mat, int m, int n) {
bool row[m], col[n];
memset(row, false, sizeof(row));
memset(col, false, sizeof(col));
for (int i = 0; i < m; ++i)
for (int j = 0; j < n; ++j)
if (mat[i][j] == 0) {
row[i] = true;
col[j] = true;
}
for (int i = 0; i < m; ++i)
for (int j = 0; j < n; ++j)
if (row[i] || col[j])
mat[i][j] = 0;
}

int main(int argc, char const *argv[]) {
int **mat;
mat[3][4] = { 1, 2, 0, 4,
4, 0, 8, 10,
3, 8, 0, 12 };
setZero(mat, 3, 4);
for (int i = 0; i < 3; ++i) {
for (int j = 0; j < 4; ++j)
cout << mat[i][j] << ' ';
cout << endl;
}
return 0;
}

上面是我写的代码, 编译的时候显示 error: expected expression
mat[3][4] = { 1, 2, 0, 4,
^
1 error generated.

各位能帮我看一下吗? 小弟水平很烂, 还请大家轻拍.

怎么发帖以后缩进全没了.......

int

mat

row

7 replies • 1970-01-01 08:00:00 +08:00

jedyu

Feb 14, 2014

定义过后，不能这么赋值

yhf

Feb 14, 2014

@jedyu 那应该怎么赋值呢? 麻烦讲详细一点好吗?

jedyu

Feb 14, 2014

int mat[3][4] = { 1, 2, 0, 4,
4, 0, 8, 10,
3, 8, 0, 12 };

yhf

Feb 14, 2014

@jedyu 可是改成这样赋值以后错误是这样的:
note: candidate function not viable: no known conversion from
'int [3][4]' to 'int **' for 1st argument
void setZero(int **mat, int m, int n) {
^
1 error generated.

jedyu

Feb 14, 2014

#include <iostream>
using namespace std;

void setZero(int mat[3][4], int m, int n)
{
if (NULL == mat || 0 ==m || n == 0)
{
return;
}

bool row[m], col[n];

for (int i = 0; i < m; i++)
{
for (int j = 0; j < n; j++)
{
if (mat[i][j] == 0)
{
row[i] = true;
col[j] = true;
}
}
}
for (int i = 0; i < m; ++i)
{
for (int j = 0; j < n; ++j)
{
if (row[i] || col[j])
{
mat[i][j] = 0;
}
}
}
}

int main(int argc, char const *argv[])
{
int mat[3][4] = { 1, 2, 0, 4,
4, 0, 8, 10,
3, 8, 0, 12 };
setZero(mat, 3, 4);
for (int i = 0; i < 3; ++i)
{
for (int j = 0; j < 4; ++j)
{
cout << mat[i][j] << ' ';
}

cout << endl;
}
return 0;
}

yhf

Feb 14, 2014

@jedyu 你这样编译是没有错误的, 但是原题的意思是不知道矩阵的大小的, 所以setZero()里面传递参数的时候不能直接把mat[3][4]传进去的吧....

jedyu

Feb 14, 2014

那你就转成char **，然后 *(mat + i * j) = ....