Bao learns patch 1

royecode/Codeforces247A.cpp

@@ -0,0 +1,48 @@
+/* ACMer: royecode
+ * Date: 2017-04-20
+ * ��Ŀ����: http://codeforces.com/contest/274/problem/A
+ * ��Ŀ����: ��һ��������n������һ��k����Ҫ�޳�����������������µ�����
+ *           y > x ���� y = x * k
+ *
+ *
+ * ����˼·: ������ȥö��yȻ����x����һ��setά��һ�´𰸣���Ȼ��Ҫ��
+ *           ���������������
+ * 
+ *
+ */
+//���벿��
+//
+#include <iostream>
+#include <vector>
+#include <set>
+
+using namespace std;
+
+int main()
+{
+    int n, k;
+    cin >> n >> k;
+    set<int> arr;
+    set<int> ans;
+
+    for(int i = 0; i < n; ++i)
+    {
+        int val;
+        cin >> val;
+        arr.insert(val);
+    }
+
+    for(set<int>::iterator begin = arr.begin(); begin != arr.end(); ++begin)
+    {
+        int val = *begin;
+        // ö��y�����y�ڴ𰸵ļ�����������
+        if(val % k == 0 && ans.find(val / k) != ans.end())
+        {
+            continue;
+        }
+        ans.insert(val);
+    }
+
+    cout << ans.size() << endl;
+    return 0;
+}

royecode/Codeforces247B.cpp

@@ -0,0 +1,71 @@
+/* ACMer: royecode
+ * Date: 2017-04-20
+ * ��Ŀ����: http://codeforces.com/contest/274/problem/B
+ * ��Ŀ����: n���ڵ������n - 1���ߣ�ÿ���ڵ��и�ֵv
+ *           ÿ������Զ�һ���������������������1����ڵ㣩��ÿ���ڵ��1���1
+ *           �����ٵIJ�����ʹ����������нڵ�ֵΪ0
+ *
+ *
+ * ����˼·: ������dfs�������ά��һ����1�ͼ�1���飬����
+ *           
+ * PS: �������˺ܾã����������ַ�������ģ�Wrong�˺ܶ��
+ *     ֮���˱��˵Ĵ���ſ����ˣ�����������
+ *
+ */
+//���벿��
+//
+#include <iostream>
+#include <algorithm>
+#include <vector>
+
+using namespace std;
+
+typedef long long ll;
+typedef pair<ll, ll> pll;
+const int N = 100007;
+
+int v[N];
+vector<int> g[N];
+
+pll dfs(int u, int p)
+{
+    ll inc = 0, dec = 0;
+    for(int i = 0; i < g[u].size(); ++i)
+    {
+        int v = g[u][i];
+        if (v == p) continue;
+
+        pll sub = dfs(v,u);
+        inc = max(inc, sub.first);
+        dec = max(dec, sub.second);
+    }
+
+    v[u] += inc - dec;
+    if(v[u] > 0) dec += v[u];
+    else inc += -v[u];
+
+    return {inc, dec};
+}
+
+int main()
+{
+    int n;
+    cin >> n;
+    for(int i = 0; i < n - 1; ++i) 
+    {
+        int x, y;
+        cin >> x >> y;
+        g[x].push_back(y);
+        g[y].push_back(x);
+    }
+
+    for(int i = 1; i <= n; ++i)
+    {
+        cin >> v[i];
+    }
+
+    pll ret = dfs(1, -1);
+
+    cout << ret.first + ret.second << endl;
+    return 0;
+}

royecode/Codeforces4102A.cpp

@@ -0,0 +1,52 @@
+/* ACMer: royecode
+ * Date: 2017-04-22
+ * 题目链接: http://codeforces.com/contest/798/problem/A
+ * 题目大意: 问字符串s，能否仅仅改变一个字符，使s为回文
+ *           能则YES，否则NO
+ *
+ *
+ * 解题思路: 令cnt为：使s为回文的最小改变次数
+ *           有两种情况为YES，cnt为1，或cnt等于0并且s的大小
+ *           为奇数。
+ *           当初考虑不完全把，Wrong了2次，尴尬！
+ * 
+ *
+ */
+//代码部分
+//
+#include <iostream>
+#include <cstdio>
+#include <cstring>
+#include <algorithm>
+#include <cmath>
+#include <vector>
+#include <string>
+#include <iterator>
+
+#define MAXN 100007
+
+using namespace std;
+
+int main()
+{
+    std::ios_base::sync_with_stdio(false);
+    string st;
+    cin >> st;
+    int times = 0;
+    for(int i = 0; i < st.length() / 2; ++i)
+    {
+        if(st[i] != st[st.length() - 1 - i])
+        {
+            times += 1;
+        }
+    }
+    if(times == 1 || (times == 0 && st.length() % 2 == 1))
+    {
+        cout << "YES" << endl;
+    }
+    else
+    {
+        cout << "NO" << endl;
+    }
+    return 0;
+}

royecode/Codeforces410Div2B.cpp

@@ -0,0 +1,79 @@
+/* ACMer: royecode
+ * Date: 2017-04-22
+ * 题目链接: http://codeforces.com/contest/798/problem/B
+ * 题目大意: n个等大小的字符串，定义移动一步：将首字符移动
+ *           末尾，用最小的移动将n个字符串变成一样的，若不
+ *           完成输出-1
+ *
+ *
+ * 解题思路: 由于字符串的大小不超过50，所以可以直接暴力模拟
+ *           时间复杂度O(n^3) 
+ *
+ */
+//代码部分
+//
+#include <iostream>
+#include <cstdio>
+#include <cstring>
+#include <algorithm>
+#include <cmath>
+#include <vector>
+#include <string>
+#include <iterator>
+
+#define MAXN 100007
+
+using namespace std;
+
+bool transform(string gold, string src, int &num)
+{
+    while(gold != src && num < gold.length())
+    {
+        src = src.substr(1, src.length() - 1) + src[0];
+        num += 1;
+    }
+
+    if(num == gold.length())
+    {
+        return false;
+    }
+    return true;
+}
+
+int main()
+{
+    std::ios_base::sync_with_stdio(false);
+    int n;
+    cin >> n;
+    vector<string> st;
+
+    for(int i = 0; i < n; ++i)
+    {
+        string temp;
+        cin >> temp;
+        st.push_back(temp);
+    }
+
+    int ans = 10000007;
+    for(int i = 0; i < n; ++i)
+    {
+        string gold = st[i];
+        int count = 0;
+        for(int i = 0; i < n; ++i)
+        {
+            int num = 0;
+            if(!transform(gold, st[i], num))
+            {
+                cout << -1 << endl;
+                return 0;
+            }
+
+            count += num;
+        }
+
+        ans = min(ans, count);
+    }
+
+    cout << ans << endl;
+    return 0;
+}