Wed, 30 Jan 2019 15:05:25 GMT

C279991/.tutorial.md

@@ -31,3 +31,7 @@ multiset.upper_bound()
 ### H - HDU Today
 
 `map/unordered_map`+单源最短路
+
+### I - Counter Strike
+
+转换为减掉平均值后求出的前缀和的顺序对数。

C279991/I.cpp

@@ -2,7 +2,41 @@
 #define _SILENCE_CXX17_C_HEADER_DEPRECATION_WARNING
 #include <bits/stdc++.h>
 using namespace std;
+const int N = 100010;
+int a[N];
+int c[N];
+#define lowbit(x) ((x) & -(x))
+int get(int x)
+{
+    int ans = 0;
+    for (; x; x -= lowbit(x)) ans += c[x];
+    return ans;
+}
+void inc(int x)
+{
+    for (; x < N; x += lowbit(x)) c[x]++;
+}
 int main()
 {
+    multiset<int> s;
+    int T, n, avg;
+    scanf("%d", &T);
+    while (T--)
+    {
+        memset(c, 0, sizeof(c));
+        long long ans = 0;
+        s.clear();
+        scanf("%d%d", &n, &avg);
+        for (int i = 1; i <= n; i++) scanf("%d", a + i), a[i] = a[i] - avg + a[i - 1];
+        vector<pair<int, int>> v(n);
+        for (int i = 1; i <= n; i++) v[i - 1] = {a[i], -i};
+        sort(begin(v), end(v));
+        for (auto &x : v)
+        {
+            ans += get(-x.second) + (x.first > 0);
+            inc(-x.second);
+        }
+        printf("%lld\n", ans);
+    }
     return 0;
 }