UVA - 11214 Guarding the Chessboard（守卫棋盘）（迭代加深搜索）

#pragma comment(linker, "/STACK:102400000, 102400000")
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<cctype>
#include<cmath>
#include<iostream>
#include<sstream>
#include<iterator>
#include<algorithm>
#include<string>
#include<vector>
#include<set>
#include<map>
#include<stack>
#include<deque>
#include<queue>
#include<list>
#define Min(a, b) ((a < b) ? a : b)
#define Max(a, b) ((a < b) ? b : a)
typedef long long ll;
typedef unsigned long long llu;
const int INT_INF = 0x3f3f3f3f;
const int INT_M_INF = 0x7f7f7f7f;
const ll LL_INF = 0x3f3f3f3f3f3f3f3f;
const ll LL_M_INF = 0x7f7f7f7f7f7f7f7f;
const int dr[] = {0, 0, -1, 1, -1, -1, 1, 1};
const int dc[] = {-1, 1, 0, 0, -1, 1, -1, 1};
const int MOD = 1e9 + 7;
const double pi = acos(-1.0);
const double eps = 1e-8;
const int MAXN = 10000 + 10;
const int MAXT = 10000 + 10;
using namespace std;
char a[15][15];
int vis[5][30];
int mark[15][15];
int kase;
int n, m;
bool judge(){
    for(int i = 0; i < n; ++i){//判断所有被标记的正方形是否被保护
        for(int j = 0; j < m; ++j){
            if(mark[i][j] && !vis[0][i] && !vis[1][j] && !vis[2][j + i] && !vis[3][j - i + n])
                return false;
        }
    }
    return true;
}
bool dfs(int cur, int pos, int tot){
    if(cur == tot){
        if(judge()){
            printf("Case %d: %d\n", kase, tot);
            return true;
        }
        return false;
    }
    else{

        for(int i = pos; i < n * m; ++i){
            int x = i / m;
            int y = i % m;
            int tmp1 = vis[0][x];
            int tmp2 = vis[1][y];
            int tmp3 = vis[2][x + y];
            int tmp4 = vis[3][y - x + n];
            vis[0][x] = vis[1][y] = vis[2][x + y] = vis[3][y - x + n] = 1;
            if(dfs(cur + 1, pos, tot)) return true;
            vis[0][x] = tmp1;
            vis[1][y] = tmp2;
            vis[2][x + y] = tmp3;
            vis[3][y - x + n] = tmp4;
        }
    }
    return false;
}
int main(){
    while(scanf("%d", &n) == 1){
        if(!n) return 0;
        ++kase;
        scanf("%d", &m);
        memset(a, 0, sizeof a);
        memset(mark, 0, sizeof mark);
        for(int i = 0; i < n; ++i){
            scanf("%s", a[i]);
        }
        for(int i = 0; i < n; ++i){
            for(int j = 0; j < m; ++j){
                if(a[i][j] == ‘X‘){
                    mark[i][j] = 1;
                }
            }
        }
        for(int i = 0; ; ++i){
            memset(vis, 0, sizeof vis);
            if(dfs(0, 0, i)) break;
        }
    }
    return 0;
}