标签：flag tin string span exactly count cond however another
In Chinese Chess, there is one kind of powerful chessmen called Cannon. It can move horizontally or vertically along the chess grid. At each move, it can either simply move to another empty cell in the same line without any other chessman along the route or perform an eat action. The eat action, however, is the main concern in this problem.
An eat action, for example, Cannon A eating chessman B, requires two conditions:
1、A and B is in either the same row or the same column in the chess grid.
2、There is exactly one chessman between A and B.
Here comes the problem.
Given an N x M chess grid, with some existing chessmen on it, you need put maximum cannon pieces into the grid, satisfying that any two cannons are not able to eat each other. It is worth nothing that we only account the cannon pieces you put in the grid, and no two pieces shares the same cell.
#include <iostream> #include <algorithm> #include <cstdio> #include <cstring> using namespace std; typedef long long LL; const int MAXN = 15; const int INF = 0x3f3f3f3f; int n, m, dis[][2] = {0, 1, 1, 0, 0, -1, -1, 0}; int vis[MAXN][MAXN], ans = 0; bool check(int x, int y) { int i, j, k; int flag; for(k = 0;k < 4;++k) { flag = 0; i = x + dis[k][0]; j = y + dis[k][1]; while(i >= 0 && j >= 0 && i < n && j < m) { if(flag && vis[i][j] == 1) return false; else if(flag && vis[i][j] == -1) break; if(vis[i][j] && !flag) flag++; i += dis[k][0]; j += dis[k][1]; } } return true; } void dfs(int x, int y, int cnt) { if(x >= n) { ans = max(ans, cnt); // cout << endl; // for(int i = 0;i < n;++i) // { // for(int j = 0;j < m;++j) // cout << vis[i][j] << " "; // cout << endl; // } return ; } if(y != m - 1) { dfs(x, y + 1, cnt); if(vis[x][y] != -1 && check(x, y)) { vis[x][y] = 1; dfs(x, y + 1, cnt + 1); vis[x][y] = 0; } } else { dfs(x + 1, 0, cnt); if(vis[x][y] != -1 && check(x, y)) { vis[x][y] = 1; dfs(x + 1, 0, cnt + 1); vis[x][y] = 0; } } } int main() { int q; while(scanf("%d%d%d", &n, &m, &q) != EOF) { memset(vis, 0, sizeof(vis)); ans = 0; int x, y; while(q--) { scanf("%d%d", &x, &y); vis[x][y] = -1; } dfs(0, 0, 0); printf("%d\n", ans); } return 0; }
标签：flag tin string span exactly count cond however another
原文地址：https://www.cnblogs.com/shuizhidao/p/9449488.html
