Codeforces Round #609 (Div. 2) 题解

  • Equation
  • Modulo Equality
  • Long Beautiful Integer
  • Domino for Young
  • K Integers

Equation

\[
Time Limit: 3 s\quad Memory Limit: 256 MB
\]
这题做法很多,甚至可以直接暴力判断

view

#include <map>
#include <set>
#include <list>
#include <ctime>
#include <cmath>
#include <stack>
#include <queue>
#include <cfloat>
#include <string>
#include <vector>
#include <cstdio>
#include <bitset>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <algorithm>
#include <unordered_map>
#define  lowbit(x)  x & (-x)
#define  mes(a, b)  memset(a, b, sizeof a)
#define  fi         first
#define  se         second
#define  pb         push_back
#define  pii        pair<int, int>

typedef unsigned long long int ull;
typedef long long int ll;
const int    maxn = 1e5 + 10;
const int    maxm = 1e5 + 10;
const ll     mod  = 1e9 + 7;
const ll     INF  = 1e18 + 100;
const int    inf  = 0x3f3f3f3f;
const double pi   = acos(-1.0);
const double eps  = 1e-8;
using namespace std;

int n, m;
int cas, tol, T;

bool ok(int a) {
    for(int i=2; i*i<=a; i++) {
        if(a%i == 0)    return 1;
    }
    return 0;
}

bool che(int a, int b) {
    return ok(a) && ok(b);
}

int main() {
    int d;
    scanf("%d", &d);
    for(int i=1000000000; i>=d; i--) {
        if(che(i, i-d)) return 0*printf("%d %d\n", i, i-d);
    }
    return 0;
}

Modulo Equality

\[
Time Limit: 3 s\quad Memory Limit: 256 MB
\]
首先 \(a[1]\) 一定会变成 \(b\) 中的某个元素,那么就可以枚举 \(a[1]\) 变成了多少,把这个数确定为 \(x\),然后判断合法性并找出所有的 \(x\)。

view

#include <map>
#include <set>
#include <list>
#include <ctime>
#include <cmath>
#include <stack>
#include <queue>
#include <cfloat>
#include <string>
#include <vector>
#include <cstdio>
#include <bitset>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <algorithm>
#include <unordered_map>
#define  lowbit(x)  x & (-x)
#define  mes(a, b)  memset(a, b, sizeof a)
#define  fi         first
#define  se         second
#define  pb         push_back
#define  pii        pair<int, int>

typedef unsigned long long int ull;
typedef long long int ll;
const int    maxn = 2e3 + 10;
const int    maxm = 1e5 + 10;
const ll     mod  = 1e9 + 7;
const ll     INF  = 1e18 + 100;
const int    inf  = 0x3f3f3f3f;
const double pi   = acos(-1.0);
const double eps  = 1e-8;
using namespace std;

int n, m;
int cas, tol, T;

int a[maxn], b[maxn];
int s[maxn];

int main() {
    scanf("%d%d", &n, &m);
    for(int i=1; i<=n; i++) scanf("%d", &a[i]);
    for(int i=1; i<=n; i++) scanf("%d", &b[i]);
    sort(a+1, a+1+n);
    sort(b+1, b+1+n);
    int ans = inf;
    for(int i=1; i<=n; i++) {
        int d = (b[i]-a[1]+m)%m;
        for(int j=1; j<=n; j++) s[j] = (a[j]+d)%m;
        sort(s+1, s+1+n);
        int f = 1;
        for(int j=1; j<=n; j++) {
            if(s[j] != b[j]) {
                f = 0;
                break;
            }
        }
        if(f)   ans = min(ans, d);
    }
    printf("%d\n", ans);
    return 0;
}

Long Beautiful Integer

\[
Time Limit: 3 s\quad Memory Limit: 256 MB
\]
可以发现最后的数字一定是以 \(k\) 为循环节一直循环的,那么我们就可以考虑一开始给出数字的前 \(k\) 位,看用这 \(k\) 位循环能否更大,如果不能的话,把这 \(k\) 位数字加一,然后在开始循环。

由于用 \(k\) 个 \(9\) 来循环一定是可以的,所以不用担心加一后位数变多的问题。

view

#include <map>
#include <set>
#include <list>
#include <ctime>
#include <cmath>
#include <stack>
#include <queue>
#include <cfloat>
#include <string>
#include <vector>
#include <cstdio>
#include <bitset>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <algorithm>
#include <unordered_map>
#define  lowbit(x)  x & (-x)
#define  mes(a, b)  memset(a, b, sizeof a)
#define  fi         first
#define  se         second
#define  pb         push_back
#define  pii        pair<int, int>

typedef unsigned long long int ull;
typedef long long int ll;
const int    maxn = 2e5 + 10;
const int    maxm = 1e5 + 10;
const ll     mod  = 1e9 + 7;
const ll     INF  = 1e18 + 100;
const int    inf  = 0x3f3f3f3f;
const double pi   = acos(-1.0);
const double eps  = 1e-8;
using namespace std;

int n, m;
int cas, tol, T;

char s[maxn], s1[maxn], s2[maxn];

bool ok() {
    for(int i=1; i<=n; i++) {
        if(s2[i] > s[i])    return true;
        if(s2[i] < s[i])    return false;
    }
    return true;
}

int main() {
    scanf("%d%d", &n, &m);
    scanf("%s", s+1);
    for(int i=1; i<=m; i++) s1[i] = s[i];
    for(int i=1, j=1; i<=n; i++) {
        s2[i] = s1[j];
        j = j%m+1;
    }
    if(ok()) return 0*printf("%d\n%s\n", n, s2+1);
    for(int i=1; i<=m; i++) s1[i] = s1[i]-'0';
    s1[m]++;
    for(int i=m; i>=1; i--) {
        if(s1[i]>=10) {
            s1[i] -= 10;
            s1[i-1] += 1;
        }
        s1[i] += '0';
    }
    for(int i=1, j=1; i<=n; i++) {
        s2[i] = s1[j];
        j = j%m+1;
    }
    printf("%d\n%s\n", n, s2+1);
    return 0;
}

Domino for Young

\[
Time Limit: 3 s\quad Memory Limit: 256 MB
\]
思维题杀我,但是这题的思路真是太优雅了。

我们把整个图看成一个国际棋盘,国际棋盘是黑白相间的,那么也就是说答案一定是 \(min\) (黑格子,白格子),因为我选了较少的那个,另一个我就一定可以找相邻的凑出来。

view

#include <map>
#include <set>
#include <list>
#include <ctime>
#include <cmath>
#include <stack>
#include <queue>
#include <cfloat>
#include <string>
#include <vector>
#include <cstdio>
#include <bitset>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <algorithm>
#include <unordered_map>
#define  lowbit(x)  x & (-x)
#define  mes(a, b)  memset(a, b, sizeof a)
#define  fi         first
#define  se         second
#define  pb         push_back
#define  pii        pair<int, int>

typedef unsigned long long int ull;
typedef long long int ll;
const int    maxn = 1e5 + 10;
const int    maxm = 1e5 + 10;
const ll     mod  = 1e9 + 7;
const ll     INF  = 1e18 + 100;
const int    inf  = 0x3f3f3f3f;
const double pi   = acos(-1.0);
const double eps  = 1e-8;
using namespace std;

int n, m;
int cas, tol, T;

int main() {
    scanf("%d", &n);
    ll ans1 = 0, ans2 = 0;
    for(int i=1, x; i<=n; i++) {
        scanf("%d", &x);
        if(i&1) ans1+=x/2, ans2+=(x+1)/2;
        else    ans2+=x/2, ans1+=(x+1)/2;
    }
    printf("%lld\n", min(ans1, ans2));
    return 0;
}

K Integers

\[
Time Limit: 3 s\quad Memory Limit: 256 MB
\]
留坑

原文地址:https://www.cnblogs.com/Jiaaaaaaaqi/p/12080426.html

时间: 2024-10-30 14:16:30

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