Codeforces Round #316 (Div. 2)

A ​​http://codeforces.com/contest/570/problem/A​​​
简单题

int n, m;

long long  cnt[1000];

struct node
{
    long long nb;
    long long sum;
}res[1000],ans[1000];

bool cmp(node a, node b)
{
    if (a.sum != b.sum)
        return a.sum > b.sum;
    else
        return a.nb < b.nb;
}

bool cmp2(int a, int b)
{

    return a > b;
}



int main()
{
    while (~scanf("%d%d", &n, &m))
    {
        memset(ans, 0, sizeof(ans));
        memset(cnt, 0, sizeof(cnt));

        long long t;
        for (int i = 1; i <= m; i++)
        {
            memset(res, 0, sizeof(res));
            for (int j = 1; j <= n; j++)
            {
                scanf("%lld",&t);
                res[j].sum += t;
                res[j].nb = j;
            }
            sort(res + 1, res + 1 + n, cmp);
            cnt[res[1].nb]++;
        }
        long long  MAX = -1;
        for (int i = 0; i <= n; i++)
            MAX = max(MAX, cnt[i]);
        for (int i = 0; i <= n; i++)
        {
            if (cnt[i] == MAX)
            {
                printf("%d\n", i);
                break;
            }
        }
    }
    return 0;
}

B ​​http://codeforces.com/contest/570/problem/B​​​
简单题

int n, m;

int main()
{
    while (~scanf("%d%d", &n, &m))
    {
        if (n == 1 && m == 1)
        {
            printf("1\n");
            continue;
        }
        int ans = n / 2;
        if (ans >= m) ans = m+1;
        else ans = m - 1;
        printf("%d\n",ans);
    }
    return 0;
}

C ​​http://codeforces.com/contest/570/problem/C​​​
思路见代码

int n, m;
char s[300010];

int main()
{
    while (~scanf("%d%d", &n, &m))
    {
        scanf("%s", s+1);
        int pos;
        char c[10];
        int ans = 0;
        for (int i = 1; i < n; i++) if (s[i] == '.' && s[i + 1] == '.') ans++;
        while (m--)
        {
            scanf("%d%s", &pos, c);
            if (pos > 1 && s[pos] == '.' && s[pos - 1] == '.') ans--;
            if (pos + 1 <= n && s[pos] == '.' && s[pos + 1] == '.') ans--;
            s[pos] = c[0];
            if (pos > 1 && s[pos] == '.' && s[pos - 1] == '.') ans++;
            if (pos + 1 <= n && s[pos] == '.' && s[pos + 1] == '.') ans++;
            printf("%d\n",ans);
        }
    }
    return 0;
}

D ​​http://codeforces.com/contest/570/problem/D​​​
代码TLE了。。。之后改

int n, m;
int deep[500010];
int fa[500010];
char s[500010];
char ss[30] = {'a','q','w','e','r','t','y','u','i','o','p','a','s','d','f','g','h','j','k','l','z','x','c','v','b','n','m'};
map<char, int>mp;
vector<int> g[500010];

void dfs(int x,int d)
{
    if (deep[x] == d)
        mp[s[x]]++;
    for (int i = 0; i < g[x].size(); i++)
    {
        if (fa[g[x][i]] == x)
            dfs(g[x][i], d);
    }
}

int main()
{
    while (~scanf("%d%d", &n, &m))
    {
        memset(fa, -1, sizeof(fa));
        for (int i = 1; i <= n; i++) g[i].clear();
        fa[1] = 1;
        deep[1] = 1;
        int max_deep = 1;

        int tmp;
        for (int i = 2; i <= n; i++)
        {
            scanf("%d", &tmp);
            g[tmp].push_back(i);
            fa[i] = tmp;
            deep[i] = deep[fa[i]] + 1;
            max_deep = max(max_deep, deep[i]);
        }
        scanf("%s", s + 1);
        int a, b;
        while (m--)
        {
            scanf("%d%d", &a, &b);
            if (b > max_deep)
            {
                puts("Yes");
                continue;
            }
            if (deep[a] > deep[b])
            {
                puts("Yes");
                continue;
            }

            mp.clear();
            dfs(a, b);
            int cnt = 0;
            for (int i = 1; i <= 26; i++)
            {
                if (mp[ss[i]] % 2 == 1) cnt++;
                if (cnt > 1) break;
            }
            //cout << "  ***  " << str << endl;
            if (cnt > 1) puts("No");
            else puts("Yes");
        }
    }
    return 0;
}