Codeforces Round 991 (Div. 3)

A. Line Breaks

https://codeforces.com/contest/2050/problem/A

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
#include<bits/stdc++.h>
using namespace std;
using u32 = unsigned;
#define i128 __int128
using ll = long long;
//#define int ll
using u64 = unsigned long long;
const ll inf = 1e9;
const ll INF = 1e18;
void solve(){
    int n,m;
    cin>>n>>m;
    ll sum=0;
    int cnt=0;
    for(int i=1;i<=n;i++)
    {
        string s;
        cin>>s;
        sum+=s.size();
        if(sum<=m)cnt++;
    }    
    cout<<cnt<<'\n';
}

signed main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int tt;cin>>tt;
    while(tt--){
        solve();
    }


    return 0;    
}

B. Transfusion

https://codeforces.com/contest/2050/problem/B

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
#include<bits/stdc++.h>
using namespace std;
using u32 = unsigned;
#define i128 __int128
using ll = long long;
//#define int ll
using u64 = unsigned long long;
const ll inf = 1e9;
const ll INF = 1e18;
void solve(){
    int n;
    cin>>n;
    vector<int>a(n+1);
    for(int i=1;i<=n;i++)cin>>a[i];
    ll sum=accumulate(a.begin()+1,a.end(),0ll);
    if(sum%n)return cout<<"NO\n",void();
    int aver=sum/n;
    for(int i=1;i<=n-2;i++)
    {
        int shu=a[i]-aver;
        a[i+2]+=shu;
    }    
    if(a[n-1]==aver&&a[n]==aver)cout<<"YES\n";
    else cout<<"NO\n";
}

signed main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int tt;cin>>tt;
    while(tt--){
        solve();
    }


    return 0;    
}

C. Uninteresting Number

https://codeforces.com/contest/2050/problem/C

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
#include <bits/stdc++.h>
using namespace std;
using u32 = unsigned;
#define i128 __int128
using ll = long long;
// #define int ll
using u64 = unsigned long long;
const ll inf = 1e9;
const ll INF = 1e18;
void solve()
{
    string s;
    cin >> s;
    int n = s.size();
    int sum = 0;
    int cnt2 = 0, cnt3 = 0;
    for (int i = 0; i < n; i++)
    {
        sum += s[i] - '0';
        if (s[i] == '2')
            cnt2++;
        else if (s[i] == '3')
            cnt3++;
    }
    sum %= 9;
    int shu = (9 - sum) % 9;
    if (shu == 0)
        return cout << "YES\n", void();
    set<int> se;
    int it;
    for (int i = 0; i <= min(cnt2, 9); i++)
    {
        for (int j = 0; j <= min(cnt3, 9); j++)
        {
            it = (2 * i + 6 * j) % 9;
            se.insert(it);
        }
    }
    if (se.contains(shu))
        cout << "YES\n";
    else
        cout << "NO\n";
}

signed main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int tt;
    cin >> tt;
    while (tt--)
    {
        solve();
    }

    return 0;
}

D. Digital string maximization

https://codeforces.com/contest/2050/problem/D

这道题就是往后看8个位置就行了，找到实际价值最大的，一直往左移就行了。

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
#include<bits/stdc++.h>
using namespace std;
using u32 = unsigned;
#define i128 __int128
using ll = long long;
//#define int ll
using u64 = unsigned long long;
const ll inf = 1e9;
const ll INF = 1e18;
void solve(){
    string s;
    cin>>s;
    int n=s.size();
    for(int i=0;i<n;i++)
    {
        int k=i;
        for(int j=i;j<n&&j<i+9;j++)
        {
            if(s[j]-j>s[k]-k)k=j;
        }
        while(k>i)
        {
            s[k]--;
            swap(s[k],s[k-1]);
            k--;
        }
    }    
    cout<<s<<'\n';
}

signed main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int tt;cin>>tt;
    while(tt--){
        solve();
    }


    return 0;    
}

E. Three Strings

https://codeforces.com/contest/2050/problem/E

看到数据范围1e3，一眼i和j双层循环，

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
#include<bits/stdc++.h>
using namespace std;
using u32 = unsigned;
#define i128 __int128
using ll = long long;
//#define int ll
using u64 = unsigned long long;
const ll inf = 1e9;
const ll INF = 1e18;
void solve(){
    string a,b,c;
    cin>>a>>b>>c;
    int n=a.size(),m=b.size();
    vector dp(n+1,vector<int>(m+1,inf));
    dp[0][0]=0;
    for(int i=0;i<=n;i++)
    {
        for(int j=0;j<=m;j++)
        {
            if(i<n)dp[i+1][j]=min(dp[i+1][j],dp[i][j]+(a[i]!=c[i+j]));
            if(j<m)dp[i][j+1]=min(dp[i][j+1],dp[i][j]+(b[j]!=c[i+j]));
        }
    }
    cout<<dp[n][m]<<'\n';
}

signed main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int tt;cin>>tt;
    while(tt--){
        solve();
    }


    return 0;    
}

F. Maximum modulo equality

https://codeforces.com/contest/2050/problem/F

这一道题可以用ST表和线段树来解决，就是用线段树维护区间内元素的差值，将+号重载为gcd就行了，找到范围内差值的最大公约数就是最终的答案。

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
#include <bits/stdc++.h>
using namespace std;
using u32 = unsigned;
#define i128 __int128
using ll = long long;
// #define int ll
using u64 = unsigned long long;
const ll inf = 1e9;
const ll INF = 1e18;
template <class Info>
struct SegmentTree
{
    int n;
    vector<Info> info;

    SegmentTree(): n(0) {}

    SegmentTree(int n, Info _init = Info())
    {
        init(vector<Info>(n, _init));
    }

    SegmentTree(const vector<Info> &_init)
    {
        init(_init);
    }

    void init(const vector<Info> &_init)
    {
        n = (int)_init.size();
        info.assign((n << 2) + 1, Info());
        function<void(int, int, int)> build = [&](int p, int l, int r)
        {
            if (l == r)
            {
                info[p] = _init[l - 1];
                return;
            }
            int m = (l + r) / 2;
            build(2 * p, l, m);
            build(2 * p + 1, m + 1, r);
            pull(p);
        };
        build(1, 1, n);
    }

    void pull(int p)
    {
        info[p] = info[2 * p] + info[2 * p + 1];
    }

    void modify(int p, int l, int r, int x, const Info &v)
    {
        if (l == r)
        {
            info[p] = v;
            return;
        }
        int m = (l + r) / 2;
        if (x <= m)
        {
            modify(2 * p, l, m, x, v);
        }
        else
        {
            modify(2 * p + 1, m + 1, r, x, v);
        }
        pull(p);
    }

    void modify(int p, const Info &v)
    {
        modify(1, 1, n, p, v);
    }

    Info query(int p, int l, int r, int x, int y)
    {
        if (l > y || r < x)
        {
            return Info();
        }
        if (l >= x && r <= y)
        {
            return info[p];
        }
        int m = (l + r) / 2;
        return query(2 * p, l, m, x, y) + query(2 * p + 1, m + 1, r, x, y);
    }

    Info query(int l, int r)
    {
        return query(1, 1, n, l, r);
    }

    int find_first(int p, int l, int r, int L, int R, const function<bool(const Info &)> &f, Info &pre)
    {
        if (l > R || r < L)
        {
            return r + 1;
        }
        if (l >= L && r <= R)
        {
            if (!f(pre + info[p]))
            {
                pre = pre + info[p];
                return r + 1;
            }
            if (l == r)
                return r;
            int m = (l + r) / 2;
            int res;
            if (f(pre + info[2 * p]))
            {
                res = find_first(2 * p, l, m, L, R, f, pre);
            }
            else
            {
                pre = pre + info[2 * p];
                res = find_first(2 * p + 1, m + 1, r, L, R, f, pre);
            }
            return res;
        }
        int m = (l + r) / 2;
        int res = m + 1;
        if (L <= m)
        {
            res = find_first(2 * p, l, m, L, R, f, pre);
        }
        if (R > m && res == m + 1)
        {
            res = find_first(2 * p + 1, m + 1, r, L, R, f, pre);
        }
        return res;
    }

    int find_first(int l, int r, const function<bool(const Info &)> &f)
    {
        Info pre = Info();
        return find_first(1, 1, n, l, r, f, pre);
    }

    int find_last(int p, int l, int r, int L, int R, const function<bool(const Info &)> &f, Info &suf)
    {
        if (l > R || r < L)
        {
            return l - 1;
        }
        if (l >= L && r <= R)
        {
            if (!f(info[p] + suf))
            {
                suf = info[p] + suf;
                return l - 1;
            }
            if (l == r)
                return r;
            int m = (l + r) / 2;
            int res;
            if (f(info[2 * p + 1] + suf))
            {
                res = find_last(2 * p + 1, m + 1, r, L, R, f, suf);
            }
            else
            {
                suf = info[2 * p + 1] + suf;
                res = find_last(2 * p, l, m, L, R, f, suf);
            }
            return res;
        }
        int m = (l + r) / 2;
        int res = m;
        if (R > m)
        {
            res = find_last(2 * p + 1, m + 1, r, L, R, f, suf);
        }
        if (L <= m && res == m)
        {
            res = find_last(2 * p, l, m, L, R, f, suf);
        }
        return res;
    }

    int find_last(int l, int r, const function<bool(const Info &)> &f)
    {
        Info suf = Info();
        return find_last(1, 1, n, l, r, f, suf);
    }
};
struct Info
{
    int g;
};
Info operator+(const Info& a,const Info& b)
{
    return {gcd(a.g, b.g)};
}
void solve()
{
    int n, q;
    cin >> n >> q;
    vector<int> a(n + 1);
    for (int i = 1; i <= n; i++)
        cin >> a[i];
    vector<Info> init(n);
    for (int i = 0; i < n; i++)
    {
        init[i].g = a[i + 1] - a[i];
    }
    SegmentTree<Info> seg(init);
    while (q--)
    {
        int l, r;
        cin >> l >> r;
        int t = seg.query(l + 1, r).g;
        cout << t << ' ';
    }
    cout << '\n';
}

signed main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int tt;
    cin >> tt;
    while (tt--)
    {
        solve();
    }

    return 0;
}