Codeforces Round #316 (Div. 2)

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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;}

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