Create code.cpp

LCCUP/2021Fall/LCP43.十字路口的交通/code.cpp

@@ -0,0 +1,115 @@
+class Solution {
+    unordered_map<char, pair<int,int>>Map[4];
+    int dp[21][21][21][21];
+    unordered_map<string, vector<int>>planMemo;
+public:
+    bool cross(pair<int,int>&a, pair<int,int>&b)
+    {
+        if (a.second < b.first) return false;
+        if (b.second < a.first) return false;
+        if (a.first < b.first && a.second > b.second) return false;
+        if (b.first < a.first && b.second > a.second) return false;
+        return true;
+    }
+
+    vector<int>strategy(string cars)
+    {
+        if (planMemo.find(cars)!=planMemo.end())
+            return planMemo[cars];
+
+        vector<int>rets;
+        for (int state=1; state<(1<<4); state++)
+        {
+            int flag = 1;
+            for (int i=0; i<4; i++) 
+            {
+                if (((state>>i)&1) && cars[i]=='#')
+                    flag = 0;
+            }
+            if (flag == 0) continue;
+
+            vector<pair<int,int>>lines;
+            for (int i=0; i<4; i++)
+            {
+                if ((state>>i)&1) 
+                {
+                    auto [start,end] = Map[i][cars[i]];
+                    int a = min(start, end);
+                    int b = max(start, end);                
+                    lines.push_back({a,b});                    
+                }                
+            }            
+
+            for (int i=0; i<lines.size(); i++)
+                for (int j=i+1; j<lines.size(); j++)
+                    if (cross(lines[i], lines[j]))
+                    {
+                        flag = 0;
+                        break;
+                    }
+
+            if (flag == 1)
+                rets.push_back(state);
+        }
+
+        planMemo[cars] = rets;
+        return rets;
+    }
+
+    int trafficCommand(vector<string>& directions) 
+    {        
+        Map[0]['S'] = {0,3};
+        Map[0]['W'] = {0,5};
+        Map[0]['N'] = {0,7};
+        Map[1]['W'] = {2,5};
+        Map[1]['N'] = {2,7};
+        Map[1]['E'] = {2,1};
+        Map[2]['N'] = {4,7};
+        Map[2]['E'] = {4,1};
+        Map[2]['S'] = {4,3};
+        Map[3]['E'] = {6,1};
+        Map[3]['S'] = {6,3};
+        Map[3]['W'] = {6,5};
+
+        int n0 = directions[0].size();
+        int n1 = directions[1].size();
+        int n2 = directions[2].size();
+        int n3 = directions[3].size();
+
+        directions[0]+="#";
+        directions[1]+="#";
+        directions[2]+="#";
+        directions[3]+="#";
+
+        for (int i=0; i<=n0; i++)
+            for (int j=0; j<=n1; j++)
+                for (int k=0; k<=n2; k++)
+                    for (int t=0; t<=n3; t++)
+                        dp[i][j][k][t] = INT_MAX/2;
+        dp[0][0][0][0] = 0;
+
+        for (int i=0; i<=n0; i++)
+            for (int j=0; j<=n1; j++)
+                for (int k=0; k<=n2; k++)
+                    for (int t=0; t<=n3; t++)
+                    {
+                        string cars;
+                        cars.push_back(directions[0][i]);
+                        cars.push_back(directions[1][j]);
+                        cars.push_back(directions[2][k]);
+                        cars.push_back(directions[3][t]);
+
+                        vector<int>plans = strategy(cars);                        
+                        for (int plan : plans)
+                        {                            
+                            int ii = i+ ((plan>>0)&1);
+                            int jj = j+ ((plan>>1)&1);
+                            int kk = k+ ((plan>>2)&1);
+                            int tt = t+ ((plan>>3)&1);
+                            dp[ii][jj][kk][tt] = min(dp[ii][jj][kk][tt], dp[i][j][k][t]+1);                            
+                       }
+                    }
+
+        return dp[n0][n1][n2][n3];
+    }
+};