关于十字链表法存储稀疏矩阵的问题

Question

#include<stdio.h>
#include<stdlib.h>
typedef struct OLNode
{
int i, j, e; //矩阵三元组i代表行 j代表列 e代表当前位置的数据
struct OLNode *right, *down; //指针域 右指针 下指针
}OLNode, *OLink;
typedef struct
{
OLink *rhead, *chead; //行和列链表头指针
int mu, nu, tu; //矩阵的行数,列数和非零元的个数
}CrossList;
CrossList CreateMatrix_OL(CrossList M);
void display(CrossList M);
int main()
{
CrossList M;
M.rhead = NULL;
M.chead = NULL;
M = CreateMatrix_OL(M);
printf("输出矩阵M:\n");
display(M);
return 0;
}
CrossList CreateMatrix_OL(CrossList M)
{
int m, n, t;
int i, j, e;
OLNode p, q;
printf("输入矩阵的行数、列数和非0元素个数：");
scanf("%d%d%d", &m, &n, &t);
M.mu = m;
M.nu = n;
M.tu = t;
if (!(M.rhead = (OLink)malloc((m + 1) * sizeof(OLink))) || !(M.chead = (OLink)malloc((n + 1) * sizeof(OLink))))
{
printf("初始化矩阵失败");
exit(0);
}
for (i = 1; i <= m; i++)
{
M.rhead[i] = NULL;
}
for (j = 1; j <= n; j++)
{
M.chead[j] = NULL;
}
for (scanf("%d%d%d", &i, &j, &e); 0 != i; scanf("%d%d%d", &i, &j, &e)) {
if (!(p = (OLNode*)malloc(sizeof(OLNode))))
{
printf("初始化三元组失败");
exit(0);
}
p->i = i;
p->j = j;
p->e = e;
//链接到行的指定位置
if (NULL == M.rhead[i] || M.rhead[i]->j > j)
{
p->right = M.rhead[i];
M.rhead[i] = p;
}
else
{
for (q = M.rhead[i]; (q->right) && q->right->j < j; q = q->right);
p->right = q->right;
q->right = p;
}
//链接到列的指定位置
if (NULL == M.chead[j] || M.chead[j]->i > i)
{
p->down = M.chead[j];
M.chead[j] = p;
}
else
{
for (q = M.chead[j]; (q->down) && q->down->i < i; q = q->down);
p->down = q->down;
q->down = p;
}
}
return M;
}
void display(CrossList M) {
for (int i = 1; i <= M.nu; i++)
{
if (NULL != M.chead[i])
{
OLink p = M.chead[i];
while (NULL != p)
{
printf("%d\t%d\t%d\n", p->i, p->j, p->e);
p = p->down;
}
}
}
}
其中 if (NULL == M.rhead[i] || M.rhead[i]->j > j)
{
p->right = M.rhead[i];
M.rhead[i] = p;
}
else
{
for (q = M.rhead[i]; (q->right) && q->right->j < j; q = q->right);
p->right = q->right;
q->right = p;
}
这里面的else里for的条件是什么意思不太理解

Answer 1

就是遍历链表所有节点，直到找到节点值大于等于j的节点，或者遍历到链表尾为止的意思