Codeforces Round · mfcheer

A：水
代码：

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <string>
#include <queue>
#include <set>

using namespace std;

int n, ans[110],tmp[21000],num;
int p[110][110];

int main()
{
    while (cin >> n)
    {
        set<int> q; q.clear();
        num = 0;
        for (int i = 1; i <= n; i++)
            for (int j = 1; j <= n; j++)
            {
                scanf("%d", &p[i][j]); 
                if (p[i][j] == -1)
                {
                    q.insert(i);
                    q.insert(j);
                }
                else if (p[i][j] == 0)
                {
                    q.insert(i);
                    q.insert(j);
                }
                else if (p[i][j] == 1)
                {
                    tmp[num++] = i;
                    q.insert(j);
                }
                else if (p[i][j] == 2)
                {
                    tmp[num++] = j;
                    q.insert(i);
                }
                else if (p[i][j] == 3)
                {
                    tmp[num++] = i;
                    tmp[num++] = j;
                }
            }
        for (int i = 0; i < num; i++)
            q.erase(tmp[i]);

        set<int> ::iterator it;
        cout << q.size() << endl;
        for (it = q.begin(); it != q.end(); it++)
            cout << *it << " ";
        cout << endl;
    }
    return 0;
}

B: s ，t 字符不同的位置，奇数用s 偶数t，其他位置随意。

代码：

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <string>
#include <queue>
#include <set>

using namespace std;

char s[100010],t[100010];
int ans[100010];

int main()
{
    while (cin >> s >> t)
    {
        int len = strlen(s);
        int tmp = 0;
        memset(ans,0,sizeof(ans));
        int num = 0;
        for (int i = 0; i < len; i++)
        {
            if (s[i] != t[i])
            {
                tmp++;
                ans[i] = -1;
            }
        }
        if (tmp % 2 == 1)
            puts("impossible");
        else
        {
            for (int i = 0; i < len; i++)
            {
                if (ans[i] == -1)
                {
                    num++;
                    if (num % 2 == 0) printf("%d", (s[i] - '0'));
                    else  printf("%d", (t[i] - '0'));
                }
                else  printf("%d", (s[i] - '0'));
            }
            printf("\n");
        }
    }
    return 0;
}

C：贪心直接搞

代码：

#include <vector>
#include <string>
#include <algorithm>
#include <iostream>
#include <stdio.h>

using namespace std;

const int MAXN=100010;
int n;
int dp[10010];

struct node
{
    int x;
    int y;
    int left,right;
}p[MAXN];

bool cmp(node a,node b)
{
    return a.x < b.x;
}

int main()
{
    while (cin>>n)
    {
        for(int i=1;i<=n;i++)
        {
            cin>>p[i].x>>p[i].y;
            p[i].left = p[i].x - p[i].y;
            p[i].right = p[i].x + p[i].y;
        }
        sort(p+1,p+1+n,cmp);
        int ans=0;
        int pos = -2000000000;
        for(int i=1;i<=n;i++)
        {
            if (p[i].x - p[i].y > pos)
            {
                pos = p[i].x;
                ans++;
            }
            else if (i == n || p[i].x + p[i].y < p[i+1].x)
            {
                pos = p[i].x + p[i].y;
                ans++;
            }
            else
                pos = p[i].x;
        }
        cout<<ans<<endl;
    }
    return 0;
}

D：排序直接搞，不满足条件直接不选。

代码：

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <string>
#include <queue>
#include <set>

using namespace std;

int n;
int p[100010];

int main()
{
    while (cin >> n)
    {
        for (int i = 1; i <= n; i++) cin >> p[i];
        sort(p + 1, p + 1 + n);
        long long tot = p[1];
        int ans = 1;
        for (int i = 2; i <= n; i++)
        {
            if (p[i] >= tot)
            {
                ans++;
                tot += p[i];
            }
        }
        printf("%d\n",ans);
    }
    return 0;
}

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