搜索例题 2019/7/3

例题1

#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
int n,m,x,y,map[16][16],cnt;
char ch[10];
bool vis[16][16];
void dfs(int x,int y){
    cnt++;
    vis[x][y]=1;
    if((map[x+1][y]==map[x][y])&&!vis[x+1][y])dfs(x+1,y);
    if((map[x][y+1]==map[x][y])&&!vis[x][y+1])dfs(x,y+1);
    if((map[x-1][y]==map[x][y])&&!vis[x-1][y])dfs(x-1,y);
    if((map[x][y-1]==map[x][y])&&!vis[x][y-1])dfs(x,y-1);
}
int main(){
     scanf("%d%d%d%d",&n,&m,&x,&y);
    for(int i=1;i<=n;i++){
        for(int j=1;j<=m;j++){
            scanf("%s",ch);
            if(ch[0]=='A')map[i][j]=1;
            if(ch[0]=='B')map[i][j]=2;
            if(ch[0]=='C')map[i][j]=3;
            if(ch[0]=='D')map[i][j]=4;
        }
    }
    if(!map[x][y]){
        puts("0");
        return 0;
    }
    dfs(x,y);
    printf("%d\n",cnt);
    return 0;
}

例题2

#include<iostream>
#include<cstdio>
#include<cstring>
using namespace std;
int n,k,ans,cnt[2],a[2][100010];
bool vis[100010];
int main(){
    scanf("%d%d",&n,&k);
    if(n==k){
        puts("0");
        return 0;
    }
    vis[n]=1;
    a[0][++cnt[0]]=n;
    bool f=0;
    while(1){
        ans++;
        f=!f;
        for(int i=1;i<=cnt[!f];i++){
            int cur;
            cur=a[!f][i]+1;
            if(cur<=100000&&cur>=0){
                if(!vis[cur]){
                    if(cur==k){
                        printf("%d\n",ans);
                        return 0;
                    }
                    else {
                        vis[cur]=1;
                        a[f][++cnt[f]]=cur;
                    }
                }
            }
            cur=a[!f][i]-1;
            if(cur<=100000&&cur>=0){
                if(!vis[cur]){
                    if(cur==k){
                        printf("%d\n",ans);
                        return 0;
                    }
                    else {
                        vis[cur]=1;
                        a[f][++cnt[f]]=cur;
                    }
                }
            }
            cur=a[!f][i]*2;
            if(cur<=100000&&cur>=0){
                if(!vis[cur]){
                    if(cur==k){
                        printf("%d\n",ans);
                        return 0;
                    }
                    else {
                        vis[cur]=1;
                        a[f][++cnt[f]]=cur;
                    }
                }
            }
        }
        cnt[!f]=0;
    }
    return 0;
}

例题3

https://www.cnblogs.com/yanlifneg/p/5717160.html

 

例题4

#include<cstdio>
#include<iostream>
#include<map>
#define M 45
#define ll long long
using namespace std;
ll a[M],s1[M],s2[M],n,key,ans;
map<ll,int> hash;
void dfs(int x,int sum,int flag) {
    if(!flag&&x>n/2) {
        hash[sum]++;
        return;
    }
    if(flag&&x>n) {
        ans+=hash[key-sum];
        return;
    }
    dfs(x+1,sum+a[x],flag);
    dfs(x+1,sum,flag);
}
int main() {
    cin>>n>>key;
    for(int i=1; i<=n; i++)
        cin>>a[i];
    dfs(1,0,0);
    dfs(n/2+1,0,1);
    cout<<ans;
    return 0;
}

 例题5

 

#include<bits/stdc++.h>
using namespace std;
const int maxn=20;
int a[maxn];
int cnt[maxn];
int ans;
int n,m;
void dfs(int v,int sum) {
    if(sum>=ans) return;
    if(v==n+1) {
        ans=sum;
        return;
    }
    for(int i=1; i<=sum; i++) {
        if(cnt[i]+a[v]<=m) {
            cnt[i]+=a[v];
            dfs(v+1,sum);
            cnt[i]-=a[v];
        }
    }
    cnt[sum+1]=a[v];
    dfs(v+1,sum+1);
    cnt[sum+1]=0;
}
int main() {
    cin>>n>>m;
    ans=n;
    for(int i=1; i<=n; i++) cin>>a[i];
    sort(a+1,a+1+n,greater<int>());
    dfs(1,0);
    cout<<ans<<endl;
    return 0;
}

 

 

例题6

#include<iostream>
using namespace std;
int map[6][6],target[6][6],sx,sy,ans,mp[6][6];
int e[8][2]={{1,2},{2,1},{-1,-2},{-2,-1},{1,-2},{-2,1},{-1,2},{2,-1}};
bool flag;
char ch;
void standred()
{
    target[1][1]=1;target[1][2]=1;target[1][3]=1;target[1][4]=1;target[1][5]=1;
    target[2][1]=0;target[2][2]=1;target[2][3]=1;target[2][4]=1;target[2][5]=1;
    target[3][1]=0;target[3][2]=0;target[3][3]=2;target[3][4]=1;target[3][5]=1;
    target[4][1]=0;target[4][2]=0;target[4][3]=0;target[4][4]=0;target[4][5]=1;
    target[5][1]=0;target[5][2]=0;target[5][3]=0;target[5][4]=0;target[5][5]=0;
}
int find()
{
    int c=0;
    for(int i=1;i<=5;i++)
        for(int j=1;j<=5;j++)
            if(mp[i][j]!=target[i][j])c++;
    return c;
}
void dfs(int now,int x,int y,int k)
{
    if(flag==1)return;
    int c=find();    
    if(now==k)
    {
        if(c==0)
        {ans=k;flag=1;
            return;}
    }
    if(now+c-1>k)return;
    for(int i=0;i<8;i++)
    {
        int ex=x+e[i][0],ey=y+e[i][1];
        if(ex<=5&&ex>=1&&ey<=5&&ey>=1)
        {
            swap(mp[x][y],mp[ex][ey]);
            dfs(now+1,ex,ey,k);
            swap(mp[x][y],mp[ex][ey]);
        }
    }
}
int main()
{
    int T;
    cin>>T;
    standred();
    while(T--)
    {
        for(int i=1;i<=5;i++)
          for(int j=1;j<=5;j++)
            {
                cin>>ch;
                if(ch=='*')sx=i,sy=j,map[i][j]=2;
                if(ch=='0')map[i][j]=0;
                if(ch=='1')map[i][j]=1;
                
            }
        for(int i=1;i<=15;i++)
        {
            flag=0;ans=20;
            for(int i=1;i<=5;i++)
              for(int j=1;j<=5;j++)
                mp[i][j]=map[i][j];
            dfs(0,sx,sy,i);
            if(ans==i)break;
        }
        if(ans<=15)
        cout<<ans<<endl;
        else
        cout<<-1<<endl;
    }
}

例题7

#include<iostream>
#include<cstdio>
#include<algorithm>
#define maxn 10010
using namespace std;
int n,k,f[maxn];
struct node {
    int l,r,nxt;
    bool operator < (const node b)const {
        return l<b.l;
    }
} a[maxn];
int search(int cur) {
    if(f[cur])return f[cur];
    int res=0x7fffffff,limit=0x7fffffff;
    for(int i=cur+1; i<=k; i++) {
        if(a[i].l>limit)break;
        else if(a[i].l>a[cur].r) {
            res=min(res,search(i));
            limit=min(limit,a[i].l);
        }
    }
    f[cur]=a[cur].r-a[cur].l+1;
    if(res!=0x7fffffff)return f[cur]+=res;
    else return f[cur];
}
int main() {
    scanf("%d%d",&n,&k);
    a[0].l=1;
    a[0].r=0;
    for(int i=1; i<=k; i++)scanf("%d%d",&a[i].l,&a[i].r),a[i].r+=a[i].l-1;
    sort(a+1,a+k+1);
    search(0);
    printf("%d",n-f[0]);
    return 0;
}