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authorSanto Cariotti <santo@dcariotti.me>2023-01-21 18:42:00 +0100
committerSanto Cariotti <santo@dcariotti.me>2023-01-21 18:42:00 +0100
commit2088bf7f12f583b37615969bed9747c6c2678e69 (patch)
treec3c6fa751236ecf0a959ef5d14523b8ef4b3af69 /Year_2
parenta2a8f8ce96a5d4556b598f5cd2490ed6563328fa (diff)
add matrix
Diffstat (limited to 'Year_2')
-rw-r--r--Year_2/Algorithms/matrix-chain.cc75
1 files changed, 75 insertions, 0 deletions
diff --git a/Year_2/Algorithms/matrix-chain.cc b/Year_2/Algorithms/matrix-chain.cc
new file mode 100644
index 0000000..2b87082
--- /dev/null
+++ b/Year_2/Algorithms/matrix-chain.cc
@@ -0,0 +1,75 @@
+#include <fstream>
+#include <iostream>
+#include <vector>
+#define INF 9999999
+
+using namespace std;
+
+using pii = pair<int, int>;
+
+int
+matrix_chain_multiply(vector<pii> a)
+{
+ int n = a.size();
+ int i, d, k;
+
+ int** m = new int*[n];
+
+ for (i = 0; i < n; ++i)
+ m[i] = new int[n];
+
+ for (i = 0; i < n; ++i)
+ m[i][i] = 0;
+
+ for (d = 1; d < n; ++d) {
+ for (i = 1; i < n - d; ++i) {
+ int j = d + i;
+ m[i][j] = INF;
+
+ for (k = i; k < j; ++k) {
+ int q = m[i][k] + m[k + 1][j] + a[i - 1].first * a[k].first * a[j].first;
+ if (q < m[i][j])
+ m[i][j] = q;
+ }
+ }
+ }
+
+ int result = m[1][n - 1];
+
+ for (i = 0; i < n; ++i)
+ delete[] m[i];
+
+ delete[] m;
+
+ return result;
+}
+
+int
+main(int argc, char** argv)
+{
+ int ts = (argc > 1) ? stoi(argv[1]) : 100;
+ ifstream fin("input.txt");
+ ofstream fout("output.txt");
+ string ch;
+
+ for (int i = 0; i < ts; ++i) {
+ vector<pii> v;
+ int n, x1, x2 {};
+ fin >> n;
+
+ for (int j = 0; j < n; ++j) {
+ fin >> ch;
+ auto x = ch.find('x');
+ x1 = stoi(ch.substr(1, x - 1));
+ x2 = stoi(ch.substr(x + 1, ch.length() - 1));
+ v.push_back({ x1, x2 });
+ }
+ v.push_back({ x2, 0 });
+ fout << matrix_chain_multiply(v) << endl;
+ }
+
+ fin.close();
+ fout.close();
+
+ return 0;
+}