Codeforces Round #771 (Div. 2)

比赛地址

A - Reverse

#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>

using namespace std;

const int N = 510;

int n;
int a[N];

void print()
{
    for (int i = 1; i <= n; i ++ ) printf("%d ", a[i]);
    puts("");
}

int main()
{
    int T;
    scanf("%d", &T);
    while (T -- )
    {
        scanf("%d", &n);
        for (int i = 1; i <= n; i ++ ) scanf("%d", &a[i]);

        bool flag = true;
        int l = 0, r = 0;
        for (int i = 1; i <= n; i ++ )
            if (i != a[i])
            {
                flag = false;
                l = i;
                break;
            }
        if (flag) print();
        else
        {
            for (int i = l + 1; i <= n; i ++ )
                if (a[i] == l)
                    r = i;
            for (int i = l, j = r; i < j; i ++ , j -- ) swap(a[i], a[j]);
            print();
        }
    }

    return 0;
}

B - Odd Swap Sort

#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>

using namespace std;

const int N = 1e5 + 10;

int n;
int a[N];
int odd[N], even[N];
int cnt1, cnt2;

int main()
{
    int T;
    scanf("%d", &T);
    while (T -- )
    {
        scanf("%d", &n);
        cnt1 = cnt2 = 0;
        for (int i = 0; i < n; i ++ ) 
        {
            scanf("%d", &a[i]);
            if (a[i] % 2) odd[cnt1 ++ ] = a[i];
            else even[cnt2 ++ ] = a[i];
        }    

        // 分别扫描奇数组和偶数组是否有序
        bool flag = true;
        for (int i = 0; i < cnt1 - 1; i ++ )
            if (odd[i] > odd[i + 1])
            {
                flag = false;
                break;
            }

        for (int i = 0; i < cnt2 - 1 && flag; i ++ )
            if (even[i] > even[i + 1]) 
            {
                flag = false;
                break;
            }
        if (!flag) puts("No");
        else puts("Yes");
    }

    return 0;
}

C - Inversion Graph

自己的代码，最终TLE了

#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>

using namespace std;

const int N = 1e5 + 10;

int n, idx;
int q[N], p[N], tmp[N];

int find(int x)
{
    if (p[x] != x) p[x] = find(p[x]);
    return p[x];
}

void merge_sort(int l, int r)
{
    if (l >= r) return;
    int mid = l + r >> 1;
    merge_sort(l, mid), merge_sort(mid + 1, r);

    int k = 0, i = l, j = mid + 1;
    while (i <= mid && j <= r)
        if (q[i] <= q[j]) tmp[k ++ ] = q[i ++ ];
        else 
        {
            int pj = find(q[j]);
            for (int t = i; t <= mid; t ++ ) 
            {
                int pt = find(q[t]);
                if (pt != pj) p[pt] = pj;
            }
            tmp[k ++ ] = q[j ++ ];
        }
    while (i <= mid) tmp[k ++ ] = q[i ++ ];
    while (j <= r) tmp[k ++] = q[j ++ ];

    for (int i = l, j = 0; i <= r; i ++ , j ++ ) q[i] = tmp[j];
}

int main()
{
    int T;
    scanf("%d", &T);
    while (T -- )
    {
        scanf("%d", &n);
        for (int i = 1; i <= n; i ++ ) 
        {
            scanf("%d", &q[i]);
            p[i] = i;
        }
        merge_sort(1, n);

        int cnt = 1;
        for (int i = 1; i < n; i ++ )
            if (find(i) != find(i + 1)) cnt ++ ;
        printf("%d\n", cnt);
    }

    return 0;
}

AC代码

#include<iostream>
using namespace std;
int main(){
    int t;
    cin >> t;
    while (t--) {
        int n, x, y=0,ans = 0;
        cin >> n;
        for (int i = 1; i <= n; i++) {
            cin >> x;
            y = max(y, x);
            if (y == i) ans++, cout << i << endl;
        }
        cout << ans << endl;
    }

    return 0;
}