HDU 5024 Wang Xifeng's Little Plot（广州网络赛C题）

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HDU 5024 Wang Xifeng's Little Plot

题目链接

思路：先利用记忆化搜索预处理出每个结点对应8个方向最远能走多远，然后枚举拐点记录最大值即可

代码：

#include <cstdio>#include <cstring>#include <algorithm>using namespace std;const int d[8][2] = {{-1, 0}, {0, 1}, {1, 0}, {0, -1}, {-1, 1}, {1, 1}, {1, -1}, {-1, -1}};const int N = 105;int n, sum[N][N][10];char g[N][N];int dfs(int x, int y, int dd) {if (x <= 0 || x > n || y <= 0 || y > n) return 0;if (sum[x][y][dd] != -1) return sum[x][y][dd];if (g[x][y] == '#') return sum[x][y][dd] = 0;sum[x][y][dd] = dfs(x + d[dd][0], y + d[dd][1], dd) + 1;return sum[x][y][dd];}int main() {while (~scanf("%d", &n) && n) {memset(sum, -1, sizeof(sum));for (int i = 1; i <= n; i++)scanf("%s", g[i] + 1);for (int i = 1; i <= n; i++) {for (int j = 1; j <= n; j++) {if (g[i][j] == '.') {for (int k = 0; k < 8; k++)dfs(i, j, k);}}}int ans = 0;for (int i = 1; i <= n; i++) {for (int j = 1; j <= n; j++) {for (int k = 0; k < 4; k++) {if (g[i][j] == '#') continue;ans = max(ans, sum[i][j][k] + sum[i][j][(k + 1) % 4] - 1);ans = max(ans, sum[i][j][k + 4] + sum[i][j][(k + 1) % 4 + 4] - 1);}}}printf("%d\n", ans);}return 0;}

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