diff --git "a/winter-day5/\347\275\227\346\275\207\351\230\263/7-1.cpp" "b/winter-day5/\347\275\227\346\275\207\351\230\263/7-1.cpp"
new file mode 100644
index 000000000..964f03ef9
--- /dev/null
+++ "b/winter-day5/\347\275\227\346\275\207\351\230\263/7-1.cpp"
@@ -0,0 +1,29 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+typedef long long var;
+typedef long double let;
+#define rep(i, a, b) for (int (i) = (a); (i) <= (b); ++(i))
+#define per(i, a, b) for (int (i) = (a); (i) >= (b); --(i))
+#define repl(i, t) for (int i = fi[t]; i; i = ne[i])
+
+var read() {
+	var a = 0, s = 0, c = getchar();
+	while (!isdigit(c)) s |= c == '-', c = getchar();
+	while (isdigit(c)) a = a * 10 + c - '0', c = getchar();
+	return s ? -a : a;
+}
+
+int n, a[1010];
+
+int main() {
+	n = read();
+  for (int i = 1; i <= n; ++i) a[i] = read();
+  int res = 0;
+  for (int i = 1; i <= n; ++i)
+    for (int j = i + 1; j <= n; ++j)
+      if (abs(a[i] - a[j]) == 1)
+        ++res;
+	printf("%d\n", res);
+  return 0;
+}
diff --git "a/winter-day5/\347\275\227\346\275\207\351\230\263/7-3.cpp" "b/winter-day5/\347\275\227\346\275\207\351\230\263/7-3.cpp"
new file mode 100644
index 000000000..2d66044b3
--- /dev/null
+++ "b/winter-day5/\347\275\227\346\275\207\351\230\263/7-3.cpp"
@@ -0,0 +1,26 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+typedef long long var;
+typedef long double let;
+#define rep(i, a, b) for (int (i) = (a); (i) <= (b); ++(i))
+#define per(i, a, b) for (int (i) = (a); (i) >= (b); --(i))
+#define repl(i, t) for (int i = fi[t]; i; i = ne[i])
+
+var read() {
+	var a = 0, s = 0, c = getchar();
+	while (!isdigit(c)) s |= c == '-', c = getchar();
+	while (isdigit(c)) a = a * 10 + c - '0', c = getchar();
+	return s ? -a : a;
+}
+
+const int N = 500010;
+int n, a[N];
+
+int main() {
+	n = read();
+  for (int i = 1; i <= 2 * n; ++i) a[i] = read();
+  nth_element(a + 1, a + n, a + 1 + 2 * n);
+	printf("%d\n", a[n]);
+  return 0;
+}
diff --git "a/winter-day5/\347\275\227\346\275\207\351\230\263/7-4.cpp" "b/winter-day5/\347\275\227\346\275\207\351\230\263/7-4.cpp"
new file mode 100644
index 000000000..0c700e350
--- /dev/null
+++ "b/winter-day5/\347\275\227\346\275\207\351\230\263/7-4.cpp"
@@ -0,0 +1,39 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+typedef long long var;
+typedef long double let;
+#define rep(i, a, b) for (int (i) = (a); (i) <= (b); ++(i))
+#define per(i, a, b) for (int (i) = (a); (i) >= (b); --(i))
+#define repl(i, t) for (int i = fi[t]; i; i = ne[i])
+
+var read() {
+	var a = 0, s = 0, c = getchar();
+	while (!isdigit(c)) s |= c == '-', c = getchar();
+	while (isdigit(c)) a = a * 10 + c - '0', c = getchar();
+	return s ? -a : a;
+}
+
+const int N = 500010;
+int n, a[N];
+
+int main() {
+	n = read();
+  for (int i = 1; i <= n; ++i) a[i] = read();
+  int x = read(), l = 1, r = n, mid = 1, cnt = 0;
+  while (l <= r) {
+    mid = (l + r) >> 1;
+    ++cnt;
+    if (a[mid] == x)
+      break;
+    if (a[mid] < x)
+      l = mid + 1;
+    else
+      r = mid - 1;
+  }
+  if (a[mid] != x)
+		printf("-1\n%d\n", cnt);
+  else
+		printf("%d\n%d\n", mid - 1, cnt);
+  return 0;
+}
diff --git "a/winter-day5/\347\275\227\346\275\207\351\230\263/7-5.cpp" "b/winter-day5/\347\275\227\346\275\207\351\230\263/7-5.cpp"
new file mode 100644
index 000000000..e3b371593
--- /dev/null
+++ "b/winter-day5/\347\275\227\346\275\207\351\230\263/7-5.cpp"
@@ -0,0 +1,69 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+typedef long long var;
+typedef long double let;
+#define rep(i, a, b) for (int (i) = (a); (i) <= (b); ++(i))
+#define per(i, a, b) for (int (i) = (a); (i) >= (b); --(i))
+#define repl(i, t) for (int i = fi[t]; i; i = ne[i])
+
+var read() {
+	var a = 0, s = 0, c = getchar();
+	while (!isdigit(c)) s |= c == '-', c = getchar();
+	while (isdigit(c)) a = a * 10 + c - '0', c = getchar();
+	return s ? -a : a;
+}
+
+typedef long long ll;
+const int MAXN = 500010;
+
+map<string, pair<int, string>> f;
+
+bool Check(string s1, string s2);
+
+int main() {
+	int n = read();
+  for (int i = 1; i <= n; ++i) {
+    string a, b;
+		cin >> a >> b;
+    if (b[b.size() - 1] == 'f')
+      f[a] = make_pair(2, "");
+    else if (b[b.size() - 1] == 'm')
+      f[a] = make_pair(1, "");
+    else if (b[b.size() - 1] == 'n')
+      f[a] = make_pair(1, b.substr(0, b.size() - 4));
+    else if (b[b.size() - 1] == 'r')
+      f[a] = make_pair(2, b.substr(0, b.size() - 7));
+  }
+  int m = read();
+  while (m--) {
+    string a, b, c, d;
+		cin >> a >> b >> c >> d;
+    if (f.find(a) == f.end() || f.find(c) == f.end()) {
+      cout << "NA\n";
+      continue;
+    } else if (f[a].first == f[c].first) {
+      cout << "Whatever\n";
+      continue;
+    } else if (Check(a, c))
+      cout << "Yes\n";
+    else
+      cout << "No\n";
+  }
+  return 0;
+}
+
+bool Check(string s1, string s2) {
+  int fa = 1;
+  for (string sa = s1; !sa.empty(); sa = f[sa].second, fa++) {
+    int fb = 1;
+    for (string sb = s2; !sb.empty(); sb = f[sb].second, fb++) {
+      if (fa >= 5 && fb >= 5)
+        return 1;
+      if (sa == sb && (fa < 5 || fb < 5)) {
+        return 0;
+      }
+    }
+  }
+  return 1;
+}
diff --git "a/winter-day5/\347\275\227\346\275\207\351\230\263/7-6.cpp" "b/winter-day5/\347\275\227\346\275\207\351\230\263/7-6.cpp"
new file mode 100644
index 000000000..8d84c25e2
--- /dev/null
+++ "b/winter-day5/\347\275\227\346\275\207\351\230\263/7-6.cpp"
@@ -0,0 +1,40 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+typedef long long var;
+typedef long double let;
+#define rep(i, a, b) for (int (i) = (a); (i) <= (b); ++(i))
+#define per(i, a, b) for (int (i) = (a); (i) >= (b); --(i))
+#define repl(i, t) for (int i = fi[t]; i; i = ne[i])
+
+var read() {
+	var a = 0, s = 0, c = getchar();
+	while (!isdigit(c)) s |= c == '-', c = getchar();
+	while (isdigit(c)) a = a * 10 + c - '0', c = getchar();
+	return s ? -a : a;
+}
+
+const int N = 500010;
+int n, a[N];
+
+int main() {
+  while (cin >> n) {
+    for (int i = 1; i <= n; ++i) a[i] = read();
+    sort(a + 1, a + 1 + n);
+    for (int i = 1; i <= n; ++i)
+      cout << a[i] << (i == n ? '\n' : ' ');
+    int m = read();
+    while (m--) {
+      int x = read();
+      int y = lower_bound(a + 1, a + 1 + n, x) - a;
+      if (a[y] == x)
+        cout << y;
+      else
+        cout << "0";
+      if (m)
+        cout << " ";
+    }
+    cout << "\n";
+  }
+  return 0;
+}
diff --git "a/winter-day5/\347\275\227\346\275\207\351\230\263/7-7.cpp" "b/winter-day5/\347\275\227\346\275\207\351\230\263/7-7.cpp"
new file mode 100644
index 000000000..dac38bf4a
--- /dev/null
+++ "b/winter-day5/\347\275\227\346\275\207\351\230\263/7-7.cpp"
@@ -0,0 +1,50 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+typedef long long var;
+typedef long double let;
+#define rep(i, a, b) for (int (i) = (a); (i) <= (b); ++(i))
+#define per(i, a, b) for (int (i) = (a); (i) >= (b); --(i))
+#define repl(i, t) for (int i = fi[t]; i; i = ne[i])
+
+var read() {
+	var a = 0, s = 0, c = getchar();
+	while (!isdigit(c)) s |= c == '-', c = getchar();
+	while (isdigit(c)) a = a * 10 + c - '0', c = getchar();
+	return s ? -a : a;
+}
+
+const int N = 500010;
+
+int n, m;
+var a[N];
+
+bool Check(var mid);
+
+int main() {
+	n = read(), m = read();
+  for (int i = 1; i <= n; ++i)
+		a[i] = read();
+  sort(a + 1, a + 1 + n);
+  var l = 1, r = 0x7fffffff, ans;
+  while (l <= r) {
+    var mid = (l + r) >> 1;
+    if (Check(mid))
+      ans = mid, l = mid + 1;
+    else
+      r = mid - 1;
+  }
+  cout << ans << "\n";
+  return 0;
+}
+
+bool Check(var mid) {
+  int cnt = 1;
+  var lst = a[1];
+  for (int i = 2; i <= n; ++i)
+    if (a[i] - lst >= mid)
+      lst = a[i], ++cnt;
+  if (cnt >= m)
+    return 1;
+  return 0;
+}
diff --git "a/winter-day5/\347\275\227\346\275\207\351\230\263/solution.md" "b/winter-day5/\347\275\227\346\275\207\351\230\263/solution.md"
new file mode 100644
index 000000000..ce875e78e
--- /dev/null
+++ "b/winter-day5/\347\275\227\346\275\207\351\230\263/solution.md"
@@ -0,0 +1,12 @@
+#### 7-2
+
+直接调用 sort 
+
+#### 7-3
+
+桶排序
+
+#### 7-4
+
+冒泡排序交换次数等于逆序对数量，直接离散化用树状数组做。
+
diff --git "a/winter-day6/\347\275\227\346\275\207\351\230\263/7-2.cpp" "b/winter-day6/\347\275\227\346\275\207\351\230\263/7-2.cpp"
new file mode 100644
index 000000000..3d18642e0
--- /dev/null
+++ "b/winter-day6/\347\275\227\346\275\207\351\230\263/7-2.cpp"
@@ -0,0 +1,38 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+typedef long long var;
+typedef long double let;
+#define rep(i, a, b) for (int (i) = (a); (i) <= (b); ++(i))
+#define per(i, a, b) for (int (i) = (a); (i) >= (b); --(i))
+#define repl(i, t) for (int i = fi[t]; i; i = ne[i])
+
+var read() {
+	var a = 0, s = 0, c = getchar();
+	while (!isdigit(c)) s |= c == '-', c = getchar();
+	while (isdigit(c)) a = a * 10 + c - '0', c = getchar();
+	return s ? -a : a;
+}
+
+const int N = 110;
+
+int n;
+pair<int, string> a[N];
+
+int main() {
+	n = read();
+  for (int i = 1; i <= n; ++i) {
+		string s;
+		cin >> s;
+		int v = read();
+		a[i] = make_pair(v, s);
+	}
+  sort(a + 1, a + 1 + n, [=] (const pair<int, string> a, const pair<int, string> b) {
+		if (a.first == b.first)
+			return a.second < b.second;
+		return a.first > b.first;
+	});
+  for (int i = 1; i <= n; ++i)
+    cout << a[i].second << " " << a[i].first << "\n";
+  return 0;
+}
diff --git "a/winter-day6/\347\275\227\346\275\207\351\230\263/7-3.cpp" "b/winter-day6/\347\275\227\346\275\207\351\230\263/7-3.cpp"
new file mode 100644
index 000000000..c2e4bbb16
--- /dev/null
+++ "b/winter-day6/\347\275\227\346\275\207\351\230\263/7-3.cpp"
@@ -0,0 +1,26 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+typedef long long var;
+typedef long double let;
+#define rep(i, a, b) for (int (i) = (a); (i) <= (b); ++(i))
+#define per(i, a, b) for (int (i) = (a); (i) >= (b); --(i))
+#define repl(i, t) for (int i = fi[t]; i; i = ne[i])
+
+var read() {
+	var a = 0, s = 0, c = getchar();
+	while (!isdigit(c)) s |= c == '-', c = getchar();
+	while (isdigit(c)) a = a * 10 + c - '0', c = getchar();
+	return s ? -a : a;
+}
+
+int n, a[55];
+
+int main() {
+	n = read();
+  for (int i = 1; i <= n; ++i)
+		a[read()]++;
+  for (int i = 0; i <= 50; ++i)
+		a[i] ? printf("%d:%d\n", i, a[i]) : printf("");
+  return 0;
+}
diff --git "a/winter-day6/\347\275\227\346\275\207\351\230\263/7-4.cpp" "b/winter-day6/\347\275\227\346\275\207\351\230\263/7-4.cpp"
new file mode 100644
index 000000000..8de9f7bf1
--- /dev/null
+++ "b/winter-day6/\347\275\227\346\275\207\351\230\263/7-4.cpp"
@@ -0,0 +1,47 @@
+#include<bits/stdc++.h>
+using namespace std;
+
+#define lowbit(x) (x & (-x))
+typedef long long ll;
+const int MAXN = 500010;
+
+void in(){}
+template<typename T, typename ...otr_T>
+void in(T &t, otr_T & ...otr)
+{
+    cin >> t;
+    in(otr...);
+}
+
+int n, m, a[MAXN], b[MAXN];
+ll sum[MAXN];
+
+void add(int pos, ll val)
+{
+    for(; pos <= n; pos += lowbit(pos))
+        sum[pos] += val;
+}
+
+ll ask(int pos)
+{
+    ll val = 0;
+    for(; pos; pos -= lowbit(pos))
+        val += sum[pos];
+    return val;
+}
+
+int main()
+{
+    in(n); ll ans = 0;
+    for(int i = 1; i <= n; ++i) in(b[i]), a[i] = b[i];
+    sort(b + 1, b + 1 + n);
+    m = unique(b + 1, b + 1 + n) - b - 1;
+    for(int i = 1; i <= n; ++i) a[i] = lower_bound(b + 1, b + 1 + n, a[i]) - b;
+    for(int i = n; i; --i)
+    {
+        ans += ask(a[i] - 1);
+        add(a[i], 1);
+    }
+    cout << ans << "\n";
+    return 0;
+}
\ No newline at end of file
diff --git "a/winter-day6/\347\275\227\346\275\207\351\230\263/solution.md" "b/winter-day6/\347\275\227\346\275\207\351\230\263/solution.md"
new file mode 100644
index 000000000..ce875e78e
--- /dev/null
+++ "b/winter-day6/\347\275\227\346\275\207\351\230\263/solution.md"
@@ -0,0 +1,12 @@
+#### 7-2
+
+直接调用 sort 
+
+#### 7-3
+
+桶排序
+
+#### 7-4
+
+冒泡排序交换次数等于逆序对数量，直接离散化用树状数组做。
+