Educational Codeforces Round 62

A. Detective Book

代码：

#include <bits/stdc++.h>
using namespace std;

const int maxn = 1e4 + 10;
int N;
int a[maxn];
int maxx = 0;

int main() {
    scanf("%d", &N);
    for(int i = 0; i < N; i ++)
        scanf("%d", &a[i]);

    int ans = 0;
    for(int i = 0; i < N; i ++) {
        maxx = max(a[i], maxx);
        if(maxx == i + 1) ans ++;
    }

    printf("%d\n", ans);
    return 0;
}

B. Good String

代码：

#include <bits/stdc++.h>
using namespace std;

int T, N;
string s;

int main() {
    scanf("%d", &T);
    while(T --) {
        scanf("%d", &N);
        cin >> s;
        int st, en;
        if(s[0] == '>')
            printf("0\n");
        else if(s[N - 1] == '<')
            printf("0\n");
        else {
            for(int i = 0; i < N; i ++) {
                if(s[i] == '>') {
                    st = i;
                    break;
                }
            }
            for(int i = N - 1; i >= 0; i --) {
                if(s[i] == '<') {
                    en = i;
                    break;
                }
            }
            printf("%d\n", min(st, N - 1 - en));
        }
    }
    return 0;
}

C. Playlist

优先队列 不是很会 看了题解才知道 555

代码：

#include <bits/stdc++.h>
using namespace std;

const int maxn = 3e5 + 10;
int N, K;
int sum[maxn];
int maxx = 0;

struct Node{
    long long t;
    long long b;
}node[maxn];

bool cmp(const Node &n1, const Node &n2) {
        return n1.b > n2.b;
}

int main() {
    scanf("%d%d", &N, &K);
    for(int i = 1; i <= N; i ++)
        cin >> node[i].t >> node[i].b;

    long long sum = 0, ans = 0;;
    priority_queue<long long, vector<long long>, greater<long long> > q;
    sort(node + 1, node + 1 + N, cmp);
    for(int i = 1; i <= N; i ++) {
        q.push(node[i].t);
        sum += node[i].t;
        if(q.size() > K) {
            sum -= q.top();
            q.pop();
        }
        ans = max(ans, sum * node[i].b);
    }

    cout << ans << endl;

    return 0;
}

D. Minimum Triangulation

代码：

#include <bits/stdc++.h>
using namespace std;

int N;
int dp[505];

int main() {
    dp[3] = 6;
    for(int i = 4; i <= 501; i ++)
        dp[i] = dp[i - 1] + (i * (i - 1));

    scanf("%d", &N);
    printf("%d\n", dp[N]);
    return 0;
}