From dc1f0c4c0096013799416664894c5194dc7e1f52 Mon Sep 17 00:00:00 2001
From: Yuqian Yang <crupest@crupest.life>
Date: Fri, 28 Feb 2025 23:13:39 +0800
Subject: chore(store): move everything to store.

---
 store/works/life/2020-algorithm-contest/code/5.cpp | 133 +++++++++++++++++++++
 1 file changed, 133 insertions(+)
 create mode 100644 store/works/life/2020-algorithm-contest/code/5.cpp

(limited to 'store/works/life/2020-algorithm-contest/code/5.cpp')

diff --git a/store/works/life/2020-algorithm-contest/code/5.cpp b/store/works/life/2020-algorithm-contest/code/5.cpp
new file mode 100644
index 0000000..24d3fd6
--- /dev/null
+++ b/store/works/life/2020-algorithm-contest/code/5.cpp
@@ -0,0 +1,133 @@
+#include <iostream>
+#include <string>
+#include <vector>
+#include <cassert>
+
+enum class Op
+{
+    Add,
+    Sub,
+    Mul,
+    Div
+};
+
+struct OpInfo
+{
+    explicit OpInfo(Op op) : op(op), count(0) {}
+
+    Op op;
+    int count; // operand count
+};
+
+int main()
+{
+    std::string expr;
+    std::getline(std::cin, expr);
+
+    std::vector<int> operands;
+    std::vector<OpInfo> op_infos;
+
+    for (auto c : expr)
+    {
+        if (c == '+')
+        {
+            op_infos.emplace_back(Op::Add);
+        }
+        else if (c == '-')
+        {
+            op_infos.emplace_back(Op::Sub);
+        }
+        else if (c == '*')
+        {
+            op_infos.emplace_back(Op::Mul);
+        }
+        else if (c == '/')
+        {
+            op_infos.emplace_back(Op::Div);
+        }
+        else if (c == '(')
+        {
+            if (!op_infos.empty())
+                op_infos.back().count++;
+        }
+        else if (c >= '0' && c <= '9')
+        {
+            operands.push_back(c - '0');
+            op_infos.back().count++;
+        }
+        else if (c == ')')
+        {
+            const auto &info = op_infos.back();
+            if ((info.op == Op::Sub || info.op == Op::Div) && info.count != 2)
+            {
+                std::cerr << "Sub or Div Op has not 2 operands.";
+                return 1;
+            }
+
+            switch (info.op)
+            {
+            case Op::Add:
+            {
+                int r = 0;
+                for (int i = 0; i < info.count; i++)
+                {
+                    r += operands.back();
+                    operands.pop_back();
+                }
+                operands.push_back(r);
+                op_infos.pop_back();
+                break;
+            }
+            case Op::Sub:
+            {
+                int a = operands.back();
+                operands.pop_back();
+                int b = operands.back();
+                operands.pop_back();
+                operands.push_back(b - a);
+                op_infos.pop_back();
+                break;
+            }
+            case Op::Mul:
+            {
+                int r = 1;
+                for (int i = 0; i < info.count; i++)
+                {
+                    r *= operands.back();
+                    operands.pop_back();
+                }
+                operands.push_back(r);
+                op_infos.pop_back();
+                break;
+            }
+            case Op::Div:
+            {
+                int a = operands.back();
+                operands.pop_back();
+                int b = operands.back();
+                operands.pop_back();
+                operands.push_back(b / a);
+                op_infos.pop_back();
+                break;
+            }
+            default:
+                std::terminate();
+            }
+        }
+    }
+
+    if (operands.size() != 1)
+    {
+        std::cerr << "final operand count is not 1, but " << operands.size();
+        return 1;
+    }
+    if (!op_infos.empty())
+    {
+        std::cerr << "final op_info is not empty";
+        return 1;
+    }
+
+    std::cout << operands.front();
+
+    return 0;
+}
-- 
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