UVA - 572 Oil Deposits（DFS）

题目大意：找出有多少块 @，八个方向相邻就算相连。

解题思路：用一个数组 num 标记该 @ 是否被查找过，若有则返回，八个方向递归查找相邻的 @。统计进入了几次 dfs

#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<algorithm>
char map[150][150];
int num[150][150];
int cnt, m, n;
void dfs(int r, int c, int cn) {
if (r < 0 || r >= m || c < 0 || c >= n) return;
if (map[r][c] != '@' || num[r][c]) return;
num[r][c] = cn;
dfs(r-1, c-1, cn);
dfs(r-1, c, cn);
dfs(r-1, c+1, cn);
dfs(r, c-1, cn);
dfs(r, c, cn);
dfs(r, c+1, cn);
dfs(r+1, c-1, cn);
dfs(r+1, c, cn);
dfs(r+1, c+1, cn);
}
int main() {
while (scanf("%d%d", &m, &n) != EOF && m) {
cnt = 0;
memset(num, 0, sizeof(num));

for (int i = 0; i < m; i++)
scanf("%s", map[i]);

for (int i = 0; i < m; i++)
for (int j = 0; j < n; j++)
if (map[i][j] == '@' && !num[i][j])
dfs(i, j, ++cnt);

printf("%d\n", cnt);

}
}

在家水了一周多，回校第一题。参考小紫。

#include<iostream>
#include<stdio.h>
#include<algorithm>
#include<cmath>
#include<string.h>
#include<string>
#include<queue>
#define max(a,b) ((a)>(b)?(a):(b))
#define min(a,b) ((a)<(b)?(a):(b))
const int INF = 0x3f3f3f3f;
const int NINF = -INF -1;
const int MAXN = 100+10;
using namespace std;
int dx[] = {-1, -1, -1, 0, 1, 1, 1, 0};
int dy[] = {-1, 0, 1, 1, 1, 0, -1, -1};
char map[MAXN][MAXN];
bool vis[MAXN][MAXN];
int m, n;
void dfs(int x, int y) {
vis[x][y] = 1;
for (int i = 0; i < 8; i++) {
int X = x+dx[i];
int Y = y+dy[i];
if (X < 0 || X >= n || Y < 0 || Y >= m) continue;
if (!vis[X][Y] && map[X][Y] == '@') {
dfs(X, Y);
}
}
}
int main() {
while (scanf("%d%d", &n, &m) && n+m) {
for (int i = 0; i < n; i++)
scanf("%s", map[i]);
int cnt = 0;
memset(vis, 0, sizeof(vis));
for (int i = 0; i < n; i++)
for (int j = 0; j < m; j++)
if (map[i][j] == '@' && !vis[i][j]) {
dfs(i, j);
cnt++;
}
printf("%d\n", cnt);
}
return 0;
}

2017-7-24

时隔一年，做 kuangbin 的搜索专题又碰到了，恩。。其实没什么区别= =