AtCoder Beginner Contest 089

A

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#include <cstdio >
int N;
int main()
{
    scanf("%d",&N);
    printf("%d\n",N/3);
}

B

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#include <cstdio>
#include <cctype>
#include <set>
using namespace std;
int n;
set<char> s;
char ch[2333];
int main()
{
    scanf("%d", &n);
    for (int i = 0; i < n; i++)
    {
        scanf("%s", ch);
        s.insert(ch[0]);
    }
    if (s.size() == 3)
        puts("Three");
    else
        puts("Four");
    return 0;
}

C

暴力全枚举！

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// LUOGU_RID: 174586349
#include <bits/stdc++.h>
#define int long long 
using namespace std;
int n, m, a, r, c, h, ans;
string st;
signed main()
{
    cin >> n;
    for (int i = 1; i <= n; i++)
    {
        cin >> st;
        if (st[0] == 'M')
            m++;
        if (st[0] == 'A')
            a++;
        if (st[0] == 'R')
            r++;
        if (st[0] == 'C')
            c++;
        if (st[0] == 'H')
            h++;
    } 
    ans += m * a * r;
    ans += m * a * c;
    ans += m * a * h;
    ans += m * r * c;
    ans += m * r * h;
    ans += m * c * h;
    ans += a * r * c;
    ans += a * r * h;
    ans += a * c * h;
    ans += r * c * h; 
    cout << ans << endl;
}

D

dp

转移dp[i] = dp[i - d] + abs(x[i] - x[i - d]) + abs(y[i] - y[i - d]);

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// LUOGU_RID: 174586544
#include <bits/stdc++.h>
#define int long long
using namespace std;
const int N = 9e4 + 10;
int h, w, q, d;
int nn;
int x[N], y[N];
int dp[N];
signed main()
{
    cin >> h >> w >> d;
    for (int i = 1; i <= h; i++)
    {
        for (int j = 1; j <= w; j++)
        {
            cin >> nn;
            y[nn] = j;
            x[nn] = i;
        }
    }
    for (int i = d + 1; i <= h * w; i++)
    {
        dp[i] = dp[i - d] + abs(x[i] - x[i - d]) + abs(y[i] - y[i - d]);
    }
    int l, r;
    cin >> q;
    while (q--)
    {
        cin >> l >> r;
        cout << dp[r] - dp[l] << endl;
    }
    return 0;
}