2019多校联讯 test 3 T2

Posted 2022-01-01 ljb666

 

dfs+二分答案，二分可能的伤害值

#include<bits/stdc++.h>
using namespace std;
const int maxn=1050;
int n,m;
int p[maxn][maxn];
int dx[5]=0,1,-1,0,0;
int dy[5]=0,0,0,-1,1;
int l,r;
bool flag;
bool vis[maxn][maxn];
void dfs(int x,int y,int cost)

    if(x==n)
        flag=true;
        return;
    
    for(int i=1;i<=4;i++)
    
        int xx=x+dx[i];
        int yy=y+dy[i];
        if(xx>=1&&xx<=n&&yy>=1&&yy<=m&&!vis[xx][yy]&&cost>=p[xx][yy])
        
            vis[xx][yy]=true;
            dfs(xx,yy,cost);
        
        if(flag==true) return;
    

bool check(int x)

    flag=false;
    memset(vis,0,sizeof(vis));
    dfs(1,1,x);
    if(flag) return true;
    else return false;

int main()

    scanf("%d%d",&n,&m);
    for(int i=1;i<=n;i++)
    
        for(int j=1;j<=m;j++)
        
            scanf("%d",&p[i][j]);
        
    
    l=0,r=1000;
    while(l<=r)
    
        int mid=(l+r)/2;
        if(check(mid)) r=mid-1;
        else l=mid+1;
    
    printf("%d",l);
    return 0;