【AtCoder】AGC027 題解

A - Candy Distribution Again

大意:有x個糖給n個小朋友,必須分完,小朋友獲得糖數爲一個確切值的時候小朋友會開心,求最多的開心數node

題解

直接排序而後貪心分,若是分到最後一個有剩餘那麼開心數-1便可ios

代碼

#include <bits/stdc++.h>
#define fi first
#define se second
#define pii pair<int,int>
#define mp make_pair
#define pb push_back
#define enter putchar('\n')
#define space putchar(' ')
#define MAXN 200005
#define mo 994711
//#define ivorysi
using namespace std;
typedef unsigned long long int64;
typedef long double db;
typedef unsigned int u32;
template<class T>
void read(T &res) {
    res = 0;char c = getchar();T f = 1;
    while(c < '0' || c > '9') {
        if(c == '-') f = -1;
        c = getchar();
    }
    while(c >= '0' && c <= '9') {
        res = res * 10 + c - '0';
        c = getchar();
    }
    res *= f;
}
template<class T>
void out(T x) {
    if(x < 0) {putchar('-');x = -x;}
    if(x >= 10) out(x / 10);
    putchar('0' + x % 10);
}
int64 x[MAXN],XV,sum[MAXN],ans;
pii que[MAXN];
int N; 
void Init() {
    read(N);read(XV);
        
    for(int i = 1 ; i <= N ; ++i) read(x[i]);
    ans = XV * (N + 1) + x[N] * 5;
    for(int i = 1 ; i < N ; ++i) {
        ans += 1LL * (2 * i + 3) * x[N - i];
    }  
    for(int i = 1 ; i <= N ; ++i) {
        sum[i] = sum[i - 1] + x[i];
    }
}
void Solve() {
    for(int K = 2 ; K <= N ; ++K) {
        int64 tmp = (K + N) * XV,t = 1;
        tmp += 5 * (sum[N] - sum[N - K]);
        for(int r = N - K; r >= 1 ; r -= K) {
            int l = max(1,r - K + 1);
            tmp += (2 * t + 3) * (sum[r] - sum[l - 1]);
            ++t;
        }
        
        ans = min(ans,tmp);
    }
    out(ans);enter;
}
int main() {
#ifdef ivorysi
    freopen("f1.in","r",stdin);
#endif
    Init();
    Solve();
    return 0;
}

B - Garbage Collector

大意:有一個機器人從0點出發,有n個座標位置有一個垃圾,且座標兩兩不一樣,機器人要把全部垃圾帶回0號點,也就是垃圾箱,拾起一個垃圾花費x,每次回到0點不管扔多少垃圾花費x,機器人在攜帶k個垃圾時走一步消耗能量是\((k + 1)^2\),求最小消耗能量c++

題解

顯然是走到最遠的垃圾而後回來的時候把當次要拿起來的垃圾一個一個撿起來,推一下會發現是個除掉最遠點,剩下座標乘的係數是一個等差數列
這個序列是5,5,7,9,11...優化

因爲我學傻了,我上去就寫了一個單調性優化= =愉快WAspa

咱們枚舉要扔h次,顯然咱們把數列的第一項分配給最大的h個,第二項分配給次大的h個……以此類推,每次須要計算\(\frac{N}{h}\)次,複雜度\(O(N \log N)\)code

代碼

#include <bits/stdc++.h>
#define fi first
#define se second
#define pii pair<int,int>
#define mp make_pair
#define pb push_back
#define enter putchar('\n')
#define space putchar(' ')
#define MAXN 200005
#define mo 994711
//#define ivorysi
using namespace std;
typedef unsigned long long int64;
typedef long double db;
typedef unsigned int u32;
template<class T>
void read(T &res) {
    res = 0;char c = getchar();T f = 1;
    while(c < '0' || c > '9') {
        if(c == '-') f = -1;
        c = getchar();
    }
    while(c >= '0' && c <= '9') {
        res = res * 10 + c - '0';
        c = getchar();
    }
    res *= f;
}
template<class T>
void out(T x) {
    if(x < 0) {putchar('-');x = -x;}
    if(x >= 10) out(x / 10);
    putchar('0' + x % 10);
}
struct node {
    int to,next;
}E[MAXN * 2];
int N,M,sumE,head[MAXN];
char s[MAXN];
int vis[MAXN][2];
void add(int u,int v) {
    E[++sumE].to = v;
    E[sumE].next = head[u];
    head[u] = sumE;
}
void Init() {
    read(N);read(M);
    scanf("%s",s + 1);
    int u,v;
    for(int i = 1 ; i <= M ; ++i) {
    read(u);read(v);add(u,v);add(v,u);
    }
}
bool dfs(int u,char c) {
    if(vis[u][c - 'A'] != -1) return vis[u][c - 'A'];
    vis[u][c - 'A'] = 0;
    for(int i = head[u] ; i ; i = E[i].next) {
    int v = E[i].to;
    if(c == s[v]) {
        int t = (s[u] - 'A') ^ 1;
        vis[u][c - 'A'] = 1;
        bool f = dfs(v,'A' + t);
        if(!f) {vis[u][c - 'A'] = 0;}
        else break;
    }
    }
    return vis[u][c - 'A'];
}
void Solve() {
    memset(vis,-1,sizeof(vis));
    for(int i = 1 ; i <= N ; ++i) {
    if(dfs(i,'A') && dfs(i,'B')) {puts("Yes");return;}
    }
    puts("No");
}
int main() {
#ifdef ivorysi
    freopen("f1.in","r",stdin);
#endif
    Init();
    Solve();
    return 0;
}

C - ABland Yard

大意:給一張圖,每一個頂點有字符A或字符B,問這個圖全部的路徑中是否包含AB能構成的全部串排序

題解

記憶化搜索
記vis[u]['A']表示u向下能走到一個以‘A’爲開頭全部串,u會走到一個v點,v點是‘A’,讓v向下走到一個和u不一樣的字符開頭的全部串,若是能走到那麼vis[u]['A']是1,不然vis[u]['A'] = 0,遞歸的過程當中咱們臨時把vis[u]['A‘]設成1遞歸

代碼

#include <bits/stdc++.h>
#define fi first
#define se second
#define pii pair<int,int>
#define mp make_pair
#define pb push_back
#define enter putchar('\n')
#define space putchar(' ')
#define MAXN 200005
#define mo 994711
//#define ivorysi
using namespace std;
typedef unsigned long long int64;
typedef long double db;
typedef unsigned int u32;
template<class T>
void read(T &res) {
    res = 0;char c = getchar();T f = 1;
    while(c < '0' || c > '9') {
        if(c == '-') f = -1;
        c = getchar();
    }
    while(c >= '0' && c <= '9') {
        res = res * 10 + c - '0';
        c = getchar();
    }
    res *= f;
}
template<class T>
void out(T x) {
    if(x < 0) {putchar('-');x = -x;}
    if(x >= 10) out(x / 10);
    putchar('0' + x % 10);
}
struct node {
    int to,next;
}E[MAXN * 2];
int N,M,sumE,head[MAXN];
char s[MAXN];
int vis[MAXN][2];
void add(int u,int v) {
    E[++sumE].to = v;
    E[sumE].next = head[u];
    head[u] = sumE;
}
void Init() {
    read(N);read(M);
    scanf("%s",s + 1);
    int u,v;
    for(int i = 1 ; i <= M ; ++i) {
    read(u);read(v);add(u,v);add(v,u);
    }
}
bool dfs(int u,char c) {
    if(vis[u][c - 'A'] != -1) return vis[u][c - 'A'];
    vis[u][c - 'A'] = 0;
    for(int i = head[u] ; i ; i = E[i].next) {
    int v = E[i].to;
    if(c == s[v]) {
        int t = (s[u] - 'A') ^ 1;
        vis[u][c - 'A'] = 1;
        bool f = dfs(v,'A' + t);
        if(!f) {vis[u][c - 'A'] = 0;}
        else break;
    }
    }
    return vis[u][c - 'A'];
}
void Solve() {
    memset(vis,-1,sizeof(vis));
    for(int i = 1 ; i <= N ; ++i) {
    if(dfs(i,'A') && dfs(i,'B')) {puts("Yes");return;}
    }
    puts("No");
}
int main() {
#ifdef ivorysi
    freopen("f1.in","r",stdin);
#endif
    Init();
    Solve();
    return 0;
}

D - Modulo Matrix

大意:構造一個矩陣,使得這個矩陣的數兩兩不一樣,且相鄰兩格最大值取模最小值是一個定值get

題解

首先咱們把這張圖二分染色,咱們往黑格子的值大於周圍的白格子string

白格子i + j相同的填上同一種質數
而後對於白格子i - j相同的再乘上一種質數
黑格子就是周圍白格子的lcm + 1便可

代碼

#include <bits/stdc++.h>
#define fi first
#define se second
#define pii pair<int,int>
#define mp make_pair
#define pb push_back
#define enter putchar('\n')
#define space putchar(' ')
#define MAXN 200005
#define mo 994711
//#define ivorysi
using namespace std;
typedef unsigned long long int64;
typedef long double db;
typedef unsigned int u32;
template<class T>
void read(T &res) {
    res = 0;char c = getchar();T f = 1;
    while(c < '0' || c > '9') {
        if(c == '-') f = -1;
        c = getchar();
    }
    while(c >= '0' && c <= '9') {
        res = res * 10 + c - '0';
        c = getchar();
    }
    res *= f;
}
template<class T>
void out(T x) {
    if(x < 0) {putchar('-');x = -x;}
    if(x >= 10) out(x / 10);
    putchar('0' + x % 10);
}
int N;
int64 a[505][505];
bool nonprime[50005];
int prime[50005],tot;
int dx[] = {1,0,-1,0};
int dy[] = {0,1,0,-1};
map<int64,pii > mmm;
int64 gcd(int64 a,int64 b) {
    return b == 0 ? a : gcd(b,a % b);
}
int64 Calc(int x,int y) {
    int64 res = 1;
    for(int k = 0 ; k <= 3 ; ++k) {
    int tx = x + dx[k],ty = y + dy[k];
    if(tx < 1 || tx > N || ty < 1 || ty > N) continue;
    res = res / gcd(res,a[tx][ty]) * a[tx][ty];
    }
    return res + 1;
}
void Solve() {
    read(N);
    if(N == 2) {
    puts("4 7");
    puts("23 10");
    return;
    }
    for(int i = 2 ; i <= 50000 ; ++i) {
    if(!nonprime[i]) {
        prime[++tot] = i; 
    }
    for(int j = 1 ; j <= tot ; ++j) {
        if(prime[j] > 50000 / i) break;
        nonprime[i * prime[j]] = 1;
        if(i % prime[j] == 0) break;
    }
    }
    int st = 1;
    for(int s = 2 ; s <= N + N ; s += 2) {
    for(int i = 1 ; i <= N ; ++i) {
        int j = s - i;
        if(j < 1 || j > N) continue;
        a[i][j] = prime[st];
    }
    ++st;
    }
    int k = N & 1 ? 1 - N : 2 - N;
    for(int s = k ; s <= N ; s += 2) {
    for(int i = 1 ; i <= N ; ++i) {
        int j = i - s;
        if(j < 1 || j > N) continue;
        a[i][j] = a[i][j] * prime[st];
    }
    ++st;
    } 
    for(int s = 3 ; s <= N + N ; s += 2) {
    for(int i = 1 ; i <= N ; ++i) {
        int j = s - i;
        if(j < 1 || j > N) continue;
        if(i == 409 && j == 101) {
        puts("QAQ");
        }
        a[i][j] = Calc(i,j);
        
    }
    }
    for(int i = 1 ; i <= N ; ++i) {
    for(int j = 1 ; j <= N ; ++j) {
        out(a[i][j]);
        j == N ? 0 : space;
    }
    enter;
    }
}
int main() {
#ifdef ivorysi
    freopen("f1.in","r",stdin);
#endif
    Solve();
    return 0;
}

E - ABBreviate

大意:一個串只由a和b構成,能夠把一個串中aa換成b,bb換成a,求能換成幾種串

題解

設a是1,b是2,一個區間能合併成一個字符當這個區間的和%3是1或2,且存在兩個相鄰的字符同樣

咱們若是要把s變成目標串t,能夠作的是把這個串從開頭劃分紅儘可能小的能變成t中每一個字符的區間,最後剩下的一塊和必定是0

咱們證實這個是充分的,咱們能夠把最後一段和剩下一塊合起來,不過這樣的話可能出現ababababab,不過能夠經過合理安排區間避免這點

而後就能夠用一個\(O(n)\)的dp解決了

代碼

#include <iostream>
#include <cstring>
#include <cstdio>
#include <algorithm>
#define enter putchar('\n')
#define space putchar(' ')
#define fi first
#define se second
//#define ivorysi
#define pii pair<int,int>
using namespace std;
typedef long long int64;
template<class T>
void read(T &res) {
    res = 0;char c = getchar();T f = 1;
    while(c < '0' || c > '9') {
    if(c == '-') f = -1;
    c = getchar();
    }
    while(c >= '0' && c <= '9') {
    res = res * 10 + c - '0';
    c = getchar();
    }
    res *= f;
}
 
template<class T>
void out(T x) {
    if(x < 0) {putchar('-');x = -x;}
    if(x >= 10) out(x / 10);
    putchar('0' + x % 10);
}
const int MOD = 1000000007;
int N;
char s[100005];
int nxt[100005][3],sum[100005],dp[100005];
int inc(int a,int b) {
    return a + b >= MOD ? a + b - MOD : a + b;
}
void update(int &x,int y) {
    x = inc(x,y);
}
void Solve() {
    scanf("%s",s + 1);
    N = strlen(s + 1);
    bool flag = 0;
    for(int i = 2 ; i <= N ; ++i) {
        if(s[i] == s[i - 1]) {flag = 1;break;}
    }
    if(!flag) {puts("1");return;}
    for(int i = 1 ; i <= N ; ++i) {
        sum[i] = (sum[i - 1] + (s[i] - '0')) % 3;
    }
    for(int i = 0 ; i < 3 ; ++i) nxt[N + 1][i] = N + 1;
    for(int i = N ; i >= 1 ; --i) {
        for(int j = 0 ; j < 3 ; ++j) nxt[i][j] = nxt[i + 1][j];
        nxt[i][sum[i]] = i;
    }
    dp[0] = 1;
    for(int i = 0 ; i <= N ; ++i) {
        for(int j = 1 ; j <= 2 ; ++j) {
            update(dp[nxt[i + 1][(sum[i] + j) % 3]],dp[i]);
        }
    }
    int ans = 0;
    for(int i = 1 ; i <= N ; ++i) {
        if(sum[i] == sum[N]) update(ans,dp[i]);
    }
    out(ans);enter;
}
int main() {
#ifdef ivorysi
    freopen("f1.in","r",stdin);
#endif
    Solve();
}

F - Grafting

大意:有兩棵樹,每次能夠把A樹的一個葉子拆下來連到另外一個點上,以後不能再動這個葉子,問A樹可否變成B樹,能的話最少幾回操做

題解

咱們先判斷AB是否兩棵相同的樹

而後考慮固定一個點,也就是拆掉A的某個葉子連到其餘任意一個點上,讓這個葉子當根,而後固定和根聯通,和B樹同樣的部分,以後建圖搜環看存不存在衝突

代碼

#include <iostream>
#include <cstring>
#include <cstdio>
#include <algorithm>
#define enter putchar('\n')
#define space putchar(' ')
#define fi first
#define se second
//#define ivorysi
#define pii pair<int,int>
using namespace std;
typedef long long int64;
template<class T>
void read(T &res) {
    res = 0;char c = getchar();T f = 1;
    while(c < '0' || c > '9') {
    if(c == '-') f = -1;
    c = getchar();
    }
    while(c >= '0' && c <= '9') {
    res = res * 10 + c - '0';
    c = getchar();
    }
    res *= f;
}
 
template<class T>
void out(T x) {
    if(x < 0) {putchar('-');x = -x;}
    if(x >= 10) out(x / 10);
    putchar('0' + x % 10);
}
int N;
int a[2][55][55],fa[2][55],used[55],ind[55],vis[55],ans;
struct node {
    int to,next;
}E[205];
int sumE,head[55];
void add(int u,int v) {
    E[++sumE].to = v;
    E[sumE].next = head[u];
    head[u] = sumE;
}
void dfs(int id,int u,int f) {
    fa[id][u] = f;if(id == 1) used[u] = (used[f] && (fa[0][u] == fa[1][u]));
    for(int i = 1 ; i <= N ; ++i) {
        if(i != f && a[id][u][i]) dfs(id,i,u);
    }
}
bool dfs2(int u) {
    vis[u] = 1;
    for(int i = head[u] ; i ; i = E[i].next) {
        int v = E[i].to;
        if(!vis[v]) {if(!dfs2(v)) return false;}
        else if(vis[v] == 1) return false;
    }
    vis[u] = 2;
    return true;
}
void check_r(int r) {
    used[0] = 1;
    dfs(0,r,0);dfs(1,r,0);
    memset(head,0,sizeof(head));sumE = 0;
    int s = 0;
    for(int i = 1 ; i <= N ; ++i) {
        if(!used[i]) {
            if(!used[fa[0][i]]) add(fa[0][i],i);
            if(!used[fa[1][i]]) add(i,fa[1][i]);
            ++s;
        }
    }
    memset(vis,0,sizeof(vis));
    for(int i = 1 ; i <= N ; ++i) {
        if(!vis[i] && !dfs2(i)) return;
    }
    ans = min(ans,s + 1);
}
void Solve() {
    read(N);
    memset(a,0,sizeof(a));
    memset(ind,0,sizeof(ind));
    int u,v;
    for(int i = 1 ; i < N ; ++i)  {
        read(u);read(v);
        a[0][u][v] = a[0][v][u] = 1;
        ind[u]++;ind[v]++;
    }
    for(int i = 1 ; i < N ; ++i) {
        read(u);read(v);
        a[1][u][v] = a[1][v][u] = 1;
    }
    used[0] = 1;
    dfs(0,1,0);dfs(1,1,0);
    int cnt = 0;
    for(int i = 1 ; i <= N ; ++i) {
        if(!used[i]) ++cnt;
    }
    if(!cnt) {puts("0");return;}
    ans = N + 1;
    for(int i = 1 ; i <= N ; ++i) {
        if(ind[i] == 1) {
            int f = 0;
            for(int j = 1 ; j <= N ; ++j) if(a[0][i][j]) f = j;
            a[0][i][f] = a[0][f][i] = 0;
            for(int j = 1 ; j <= N ; ++j) {
                a[0][i][j] = a[0][j][i] = 1;
                check_r(i);
                a[0][i][j] = a[0][j][i] = 0;
            }
            a[0][i][f] = a[0][f][i] = 1;
        }
    }
    if(ans == N + 1) {puts("-1");}
    else {out(ans);enter;}
}
int main() {
#ifdef ivorysi
    freopen("f1.in","r",stdin);
#endif
    int T;
    read(T);
    while(T--) {
        Solve();
    }
    return 0;
}
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