PE 081, finished by simple dynamic program

projecteuler/081/main.cpp

@@ -0,0 +1,61 @@
+
+
+#include <bits/stdc++.h>
+
+using namespace std;
+
+int main(){
+
+    cout << "Hello this is Patrick" << endl;
+    auto start = chrono::high_resolution_clock::now();
+
+    // I imagine we have to do something with memoization, building up the cheapest path from
+    // the bottom right corner up to the top left corner
+
+    // First read the matrix file
+
+    vector<vector<long long>> matrix(80);
+
+    ifstream matrixFile("matrix.txt");
+
+    for(int i = 0; i < 80; ++i){
+        for(int j = 0; j < 80; ++j){
+            int n;
+            matrixFile >> n;
+
+            matrix[i].push_back(n);
+
+            if(j != 79){
+                char c;
+                matrixFile >> c;
+            }
+        }
+    }
+
+    vector<vector<long long>> dp(80);
+    for(int i = 0; i < 80; ++i){
+        for(int j = 0; j < 80; ++j){
+            dp[i].push_back(-1);
+        }
+    }
+
+    dp[79][79] = matrix[79][79];
+    for(int i = 78; i >= 0; --i){
+        dp[i][79] = matrix[i][79] + dp[i+1][79];
+    }
+    for(int j = 78; j >= 0; --j){
+        dp[79][j] = matrix[79][j] + dp[79][j+1];
+    }
+
+    for(int i = 78; i >= 0; --i){
+        for(int j = 78; j >= 0; --j){
+            dp[i][j] = matrix[i][j] + min(dp[i+1][j], dp[i][j+1]);
+        }
+    }
+
+    cout << dp[0][0] << endl;
+
+    auto duration = chrono::duration_cast<chrono::milliseconds>(chrono::high_resolution_clock::now() - start);
+    cout << (float)duration.count()/1000 << endl;
+    return 0;
+}