2020 ICPC·Xiaomi Internet Trial Tournament First Walking Machine

Walking Machine
topic
in a $n\ast$Search in the matrix of$m$ , each character has a different meaning, such as:
$W$ means from ($x$ ,$y$ ) can go to ($x-1$ ,$y$ )
$A$ means from ($x$ ,$y$ ) can go to ($x$ ,$and-1$)
$S$ means from ($x$ ,$y$ ) can go to ($x+1$ ,$y$)
$D$ means from ($x$ ,$y$ ) can go to ($x$ ,$and+1$ )
Request which points will cross the boundary, that is, point coordinates ($x$ ,$y$ )$x$ <1 or$x$ > $n$ , or$y$ <1 ， 或者$y$ > $m$ .
Input format
input$n$ and$m$ represents the size of the matrix.
Next$n$ rows, each row$m$ characters.
Output format
Output an integer, indicating the number of points out of bounds. The comprehensive application of
problem solving ideas
and search set and dfs
splits the matrix into$n$*$m$ points, record the position of each point, and then use the idea of ​​union search to merge all out-of-bounds points into a set, and finallyfindall pointsClick$f$$i$$n$$d$ , and record the number of points out of bounds is the answer.

#include <cstdio>
#include <algorithm>
using namespace std;
const int maxn = 1e6 + 7, inf = 1e8;
struct node{
    
    
    int x,y;
    char s;
};
node a[maxn];
int fa[maxn], cnt = 0;

char str[1007][1007];
bool inbound(int x, int l, int r)
{
    
    
    if(x < l || x > r) return false;
    return true;
}
void Init(int x)  //初始化
{
    
    
    for(int i = 1; i <= x; i++) fa[i] = i;
}
int Find(int x)  //查询，路径压缩
{
    
    
    if(fa[x] != x) fa[x] = Find(fa[x]);
    return fa[x];
}
void Merge(int x, int y)  //合并
{
    
    
    int fax = Find(x), fay = Find(y);
    fa[fax] = fay;
}

int main()
{
    
    
    int n,m;
    scanf(" %d%d",&n,&m);
    for(int i = 1; i <= n; i++)
        for(int j = 1; j <= m; j++){
    
    
            scanf(" %c",&str[i][j]);
            a[++cnt] = {
    
    i, j, str[i][j]};
        }

    Init(cnt+1);
    for(int i = 1; i <= cnt; i++)
    {
    
    
        int x = a[i].x, y = a[i].y; char s = a[i].s;
        int num = (x-1)*m + y;
        int tx = 0, ty = 0, tnum = 0;

        if(s == 'W') tx = x -  1, ty = y;
        if(s == 'A') tx = x, ty = y - 1;
        if(s == 'S') tx = x + 1, ty = y;
        if(s == 'D') tx = x, ty = y + 1;

        if(!inbound(tx, 1, n) || !inbound(ty, 1, m)) Merge(num, cnt+1);
        else
        {
    
    
             tnum = (tx - 1)*m + ty;
             if(Find(num) != Find(tnum)) Merge(num, tnum);
        }
    }

    int res = 0;
    for(int i = 1; i <= cnt; i++)
        if(Find(i) == cnt+1) res++;
    printf("%d\n",res);
    return 0;
}