2021年暑假康复性训练(Codeforces Round #731 (Div. 4))全题解(下)

简介: D. Co-growing Sequenceinput:output:code:E. Air Conditionersinput:output:F. Array Stabilization (GCD version)input:output:code:G. How Many Paths?input:output:ac_code:

D. Co-growing Sequence


20210712233416174.png


input:


5
4
1 3 7 15
4
1 2 4 8
5
1 2 3 4 5
4
11 13 15 1
1
0


output:


0 0 0 0 
0 1 3 7 
0 1 0 3 2 
0 2 0 14 
0 


code:


int a[maxn<<1],b[maxn<<1];
int main()
{
    int _ = read;
    while(_ --){
        int n = read;
        for(int i=1;i<=n;i++){
            a[i] = read;
            if(i >= 2){
                int temp = (a[i] | a[i-1]);
                b[i] = a[i] ^ temp;
                a[i] = temp;
            }
        }
        for(int i = 1;i <= n;i++){
            printf("%d ",b[i]);
        }puts("");
    }
    return 0;
}


E. Air Conditioners


20210712233623177.png


input:


5
6 2
2 5
14 16
10 1
7
30
5 5
3 1 4 2 5
3 1 4 2 5
7 1
1
1000000000
6 3
6 1 3
5 5 5


output:


15 14 15 16 16 17 
36 35 34 33 32 31 30 31 32 33 
1 2 3 4 5 
1000000000 1000000001 1000000002 1000000003 1000000004 1000000005 1000000006 
5 6 5 6 6 5 


int a[maxn << 1], b[maxn << 1];
typedef pair<int, int> PII;
vector<PII> vet;
int main()
{
    int _ = read;
    while(_ --)
    {
        memset(b,0x3f3f3f3f,sizeof b);
        int n = read, m = read;
        for(int i = 1; i <= m; i++) a[i] = read;
        for(int i = 1; i <= m; i++)
        {
            b[a[i]] = read;
        }
        for(int i = 1; i <= n; i++) b[i] = min(b[i], b[i - 1] + 1);
        for(int i = n - 1; i >= 1; i--) b[i] = min(b[i], b[i + 1] + 1);
        for(itn i = 1; i <= n; i++)
        {
            printf("%d ", b[i]);
        }
        puts("");
    }
    return 0;
}


另一种做法:


int n, m;
struct node{
    int u,v,w,nex;
}e[maxn];
int head[maxn << 1],cnt,dis[maxn << 1],a[maxn << 1];
bool vis[maxn << 1];
void init(int x){
    cnt = 0;
    for(int i=1;i<=x;i++) head[i] = -1,vis[i] = 0,dis[i] = INF;
}
void add(int u,int v,int w){
    e[cnt].u = u;
    e[cnt].v = v;
    e[cnt].w = w;
    e[cnt].nex = head[u];
    head[u] = cnt++;
}
typedef pair<int,int> PII;
void dijkstra(int x){
    priority_queue<PII,vector<PII>, greater<PII> > que;
    dis[x] = 0;
    vis[x] = 1;
    que.push({0,x});
    while(que.size()){
        PII t = que.top();que.pop();
        int u = t.second;
        int w = t.first;
        vis[u] = 0;
        for(int i=head[u];~i;i=e[i].nex){
            int to = e[i].v;
            int w = e[i].w;
            if(dis[to] > dis[u] + w){
                dis[to] = dis[u] + w;
                if(!vis[to]){
                    que.push({dis[to],to});
                }
            }
        }
    }
}
int main() {
    int _ = read;
    while(_ --){
        int n = read,k = read;
        init(n + 1000);
        int pt = n + 1;
        for(int i=1;i<=k;i++) a[i] = read;
        for(int i=1;i<=k;i++){
            int w = read;
            add(pt,a[i],w);
        }
        for(int i=1;i<=n;i++){
            if(i != 1) add(i,i-1,1);
            if(i != n) add(i,i+1,1);
        }
        dijkstra(pt);
        for(int i=1;i<=n;i++) printf("%d ",dis[i]);
        puts("");
    }
  return 0;
}


F. Array Stabilization (GCD version)


20210713233133341.png


input:


5
4
16 24 10 5
4
42 42 42 42
3
4 6 4
5
1 2 3 4 5
6
9 9 27 9 9 63


output:


3
0
2
1
1


code:


首先是一个错误的代码,但是可以ac的

int n;
int st[maxn][21];
int a[maxn << 1],b[maxn << 1];
int get(int i,int j){
    int t = log2(j-i+1);
    return gcd(st[i][t], st[j-(1<<t)+1][t]);
}
int main() {
    int _ = read;
    while(_ --){
        n = read;
        for(int i=1;i<=n;i++)
            st[i][0] = st[i+n][0] = a[i+n] = a[i] = read,b[i] = 0;
        int ans = 0,flag = 0;
        for(int i=1;i<=n;i++){
            if(a[i] != a[1]) flag = 1;
        }
        if(!flag) {
            cout << 0 <<endl;
            continue;
        }
        int gd = a[1];
        for(int i=2;i<=n;i++) gd = gcd(gd,a[i]);
        ///cout << gd <<endl;
        int lim = 2 * n;
        for(int j=1;(1<<j) <= lim;j ++){
            for(int i=1;i + (1 << j) - 1 <= lim;i ++){
                st[i][j] = gcd(st[i][j-1],st[i+(1<<j-1)][j-1]);//错误!!!!!!
            }
        }
        for(int i=1;i<=n;i++){
            int l = i, r = n + i - 1;/// n + i - 1 - i + 1 == n
            while(l < r){
                int mid = l + r >> 1;
                if(get(i,mid) != gd) l = mid + 1;
                else r = mid;
            }
            ans = max(ans,l-i);
        }
        cout << ans <<endl;
    }
  return 0;
}


正确代码:

int n;
int st[maxn][21];
int a[maxn << 1],b[maxn << 1];
int get(int i,int j){
    int t = log2(j-i+1);
    return gcd(st[i][t], st[j-(1<<t)+1][t]);
}
int main() {
    int _ = read;
    while(_ --){
        n = read;
        for(int i=1;i<=n;i++)
            st[i][0] = st[i+n][0] = a[i+n] = a[i] = read,b[i] = 0;
        int ans = 0,flag = 0;
        for(int i=1;i<=n;i++){
            if(a[i] != a[1]) flag = 1;
        }
        if(!flag) {
            cout << 0 <<endl;
            continue;
        }
        int gd = a[1];
        for(int i=2;i<=n;i++) gd = gcd(gd,a[i]);
        ///cout << gd <<endl;
        int lim = 2 * n;
        for(int j=1;(1<<j) <= lim;j ++){
            for(int i=1;i + (1 << j) - 1 <= lim;i ++){
                st[i][j] = gcd(st[i][j-1],st[i+(1<<(j-1))][j-1]);/// 1 << (j-1) 2 ^j-1^
            }
        }
        for(int i=1;i<=n;i++){
            int l = i, r = n + i - 1;/// n + i - 1 - i + 1 == n
            while(l < r){
                int mid = l + r >> 1;
                if(get(i,mid) != gd) l = mid + 1;
                else r = mid;
            }
            ans = max(ans,l-i);
        }
        cout << ans <<endl;
    }
  return 0;
}


G. How Many Paths?


20210714144809186.png

2021071414482461.png


input:


5
6 7
1 4
1 3
3 4
4 5
2 1
5 5
5 6
1 0
3 3
1 2
2 3
3 1
5 0
4 4
1 2
2 3
1 4
4 3


output:


1 0 1 2 -1 -1 
1 
-1 -1 -1 
1 0 0 0 0 
1 1 2 1 


ac_code:


typedef int itn;
int n,m,cnt,head[maxn];
int col[maxn],col2[2][maxn];
set<int> s[2];
struct node{
    int u,v,nex;
}e[maxn];
void init(int x){
    cnt = 0;
    for(int i=0;i<=x + 1;i++) head[i] = -1,col[i] = 0,col2[0][i] = col2[1][i] = 0;
}
void add(int u,int v){
    e[cnt].u = u;
    e[cnt].v = v;
    e[cnt].nex = head[u];
    head[u] = cnt ++;
}
void dfs1(int u){
    /**
    value = 0 -> not used
    value = 1 -> using
    value = 2 -> used
    **/
    col[u] = 1;/// using
    for(int i = head[u];~i; i = e[i].nex){
        int to = e[i].v;
        if(col[to] == 0) dfs1(to);
        else{
            int t = col[to];
            s[t-1].insert(to);
        }
    }
    col[u] = 2;/// used
}
void dfs2(int u,int lev){
    /** the same like dfs1
    value = 0 -> not used
    value = 1 -> using
    value = 2 -> used
    **/
    col2[lev][u] = 1;
    for(int i=head[u];~i;i=e[i].nex){
        int to = e[i].v;
        if(col2[lev][to] == 0) dfs2(to,lev);
    }
    col2[lev][u] = 2;
}
int main() {
    int _ = read;
    while(_ --){
        n = read, m = read;
        init(n);
        s[0] = s[1] = set<int>();
        for(int i=1;i<=m;i++){
            int u = read,v = read;
            u--,v--;
            add(u,v);
        }///build edge
        dfs1(0);/// use col
        for(int i=0;i<=1;i++){
            for(auto u: s[i]){
                dfs2(u,i);
            }
        }
        for(int i=0;i<n;i++){
            int t = 0;
            if(col[i] != 0){
                t = 1;
                if(col2[0][i]) t = -1;
                else if(col2[1][i]) t = 2;
            }
            printf("%d ",t);
        }
        puts("");
    }
  return 0;
}
/**
5
6 7
1 4
1 3
3 4
4 5
2 1
5 5
5 6
1 0
3 3
1 2
2 3
3 1
5 0
4 4
1 2
2 3
1 4
4 3
**/


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