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Algorithm/DP-DynamicProgramming/Bitmask-DP/货郎担问题TSP.cpp

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+#include <iostream>
+#include <vector>
+using namespace std;
+const int MAX = INT_MAX >> 1;
+int main(){
+	//n <= 15, S<><53><EFBFBD><EFBFBD><EFBFBD><EFBFBD>15λ<35>Ķ<EFBFBD><C4B6><EFBFBD><EFBFBD><EFBFBD> 
+	int n;
+	cin >> n;
+	//<2F><>0<EFBFBD><30>ʼ
+	vector<vector<int>> dist(n, vector<int>(n, 0));
+	vector<vector<int>> dp(n, vector<int>(1 << n, MAX));//dp[i][S]; 
+	int N = 1 << n; // 2 ^ n;
+	for(int i = 0; i < n; i++){
+		for(int j = 0; j < n; j++){
+			cin >> dist[i][j]; 
+		}
+	}
+	int start, end;
+	cin >> start >> end;
+	dp[start][1 << start] = 0;
+	//S<><53><EFBFBD><EFBFBD><EFBFBD>ij<EFBFBD><C4B3><EFBFBD> 
+	//<2F><>ʼ<EFBFBD><CABC><EFBFBD><EFBFBD> 
+	for(int mask = 0; mask < N; mask++){
+		for(int j = 0; j < n; j++){
+			if(dp[j][mask] == MAX || !(mask & (1 << j))) continue;
+			
+			for(int v = 0; v < n; v++){
+				if(mask & (1 << v)) continue; 
+				int new_mask = mask | (1 << v);
+				//1001 | 0001 = 1001, 1001 ^ 0001 = 1000
+				dp[v][new_mask] = min(dp[v][new_mask], dp[j][mask] + dist[j][v]);
+			}
+		}
+	}
+	// <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD>С·<D0A1><C2B7><EFBFBD><EFBFBD><EFBFBD>յ<EFBFBD>Ϊ end<6E><64><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>г<EFBFBD><D0B3><EFBFBD>
+    int full_mask = (1 << n) - 1; // <20><><EFBFBD>г<EFBFBD><D0B3>ж<EFBFBD><D0B6><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>
+    int cost = dp[end][full_mask];
+    if (cost == MAX) {
+        cout << "No valid path" << endl; // û<>п<EFBFBD><D0BF><EFBFBD>·<EFBFBD><C2B7>
+    } else {
+        cout << cost << endl;
+    }
+	return 0;
+}
+/*
+4
+0 10 15 20
+10 0 35 25
+15 35 0 30
+20 25 30 0
+0 3
+*/