2015安徽省赛 I.梯田

http://xcacm.hfut.edu.cn/problem.php?id=1213

set + 搜索

姐姐是用搜索+二分做的，效率要高很多

#include<iostream>
#include<cstdio>
#include<cstring>
#include<set>
using namespace std;
int x[]={ 0, 0,-1, 1};
int y[]={ 1,-1, 0, 0};
int lable[105][105],d[105][105];
int T,m,n,p,q,deepth=0,cake=0;
void dfs(int a,int b)
{
    if(d[a][b]>deepth||a<0||a>=m||b<0||b>=n||lable[a][b]==1){return;}
    lable[a][b]=1;
    cake++;
    for(int i=0;i<4;i++)
    {
        if(a+x[i]<0||a+x[i]>=m||b+y[i]<0||b+y[i]>=n){continue;}
        dfs(a+x[i],b+y[i]);
    }
    return;
}
void solve()
{
    int i,j;
    for(i=0; i<m; i++)
    {
        if(lable[i][0]==1)
        {
            continue;
        }
        dfs(i,0);
    }
    for(i=0; i<m; i++)
    {
        if(lable[i][n-1]==1)
        {
            continue;
        }
        dfs(i,n-1);
    }
    for(j=0; j<n; j++)
    {
        if(lable[0][j]==1)
        {
            continue;
        }
        dfs(0,j);
    }
    for(j=0; j<n; j++)
    {
        if(lable[m-1][j]==1)
        {
            continue;
        }
        dfs(m-1,j);
    }
}

int main()
{
    int i,j;
    scanf("%d",&T);
    while(T--)
    {
        scanf("%d%d%d%d",&m,&n,&p,&q);
        set<int>donser;
        for(i=0;i<m;i++)
        {
            for(j=0;j<n;j++)
            {
                scanf("%d",&d[i][j]);
                donser.insert(d[i][j]);
            }
        }
        while(1)
        {
            deepth=*donser.begin();
            solve();
            donser.erase(deepth);
            if(cake>=p&&cake<=q)
            {
                cout<<deepth<<endl;
                cake=0;
                memset(lable,0,sizeof(lable));
                memset(d,0,sizeof(d));
                break;
            }
            if(donser.size()==0||cake>q)
            {
                cout<<"-1"<<endl;
                cake=0;
                memset(lable,0,sizeof(lable));
                memset(d,0,sizeof(d));
                break;
            }
            cake=0;
            memset(lable,0,sizeof(lable));
        }
    }
    return 0;
}