add BOI7SEQ

boi7seq.cpp

@@ -0,0 +1,39 @@
+// 2016-04-28
+#include <cstdio>
+#include <vector>
+using namespace std;
+int input() {
+    int res = 0; char c;
+    do {
+        c = getchar_unlocked();
+    } while (c <= 32);
+    do {
+        res = res*10 + c - '0';
+        c = getchar_unlocked();
+    } while (c > 32);
+    return res;
+}
+int main() {
+    int n = input();
+    long long total = 0;
+    vector<int> stk;
+    stk.push_back(input());
+    for (int i = 1; i < n; i++) {
+        int x = input();
+        if (x >= stk.back()) {
+            while (stk.size() >= 1 && x >= stk.back()) {
+                stk.pop_back();
+                if (stk.empty() || x < stk.back()) {
+                    total += x;
+                } else {
+                    total += stk.back();
+                }
+            }
+        }
+        stk.push_back(x);
+    }
+    for (int i = 0; i+1 < stk.size(); i++) {
+        total += stk[i];
+    }
+    printf("%lld\n", total);
+}