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@@ -0,0 +1,100 @@
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+#include <iostream>
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+#include <cstdlib>
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+#include <string>
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+
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+/*int n;
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+int twon = 2 * n;
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+int * a;
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+int * b;
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+int * sums = malloc(2 * sizeof(b));
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+int pos = 0;
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+
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+for (int i = 0; i < twon; i++)
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+{
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+ for (int j = (i + 1); j < twon; j++, pos++)
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+ {
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+ sums[pos] = b[i] + b[j];
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+ }
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+}
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+
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+sort c;
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+
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+for (int i = 0; i < twon; i++)
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+{
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+ for (int j = (i + 1); j < twon; j++, pos++)
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+ {
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+ if sums.search(a[i] + a[j]) return true;
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+ }
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+}
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+
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+return false;
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+
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+================*/
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+
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+int n;
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+std::cin >> n; // get the length of the array we are manipulating
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+
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+int * a = malloc(n * sizeof(int));
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+int * b = malloc(n * sizeof(int));
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+
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+for (int i = 0; i < n; ++i)
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+{
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+ // get each line which is 2 ints, put into A and B
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+ std::string input;
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+ std::getline(std::cin, input);
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+ std::stringstream nums(input);
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+
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+ nums >> a[i];
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+ nums >> b[i];
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+}
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+
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+/*
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+int clen = 2 * n;
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+int * C = malloc(clen * sizeof(int)); // to hold the list of possible sums
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+int tempcount = 0;
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+
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+for (int i = 0; i < n; i++)
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+{
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+ for (int j = (i + 1); j < n; ++j, ++tempcount)
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+ {
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+ C[tempcount] = (B[i] + B[j]);
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+ C[clen - tempcount - 1] = (A[i] + A[j]);
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+ }
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+} // n squared
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+
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+sort(C, C + clen); // n^2 log n squared == n^2 log n */
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+
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+int clen = (n * (n - 1)) / 2; // total possible sums in an array of length n
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+int * c = malloc(clen * sizeof(int));
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+int tempcount = 0;
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+
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+// Store within c the possible sums inside b
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+for (int i = 0; i < n; ++i)
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+{
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+ for (int j = (i + 1); j < n; ++j, ++tempcount)
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+ {
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+ c[tempcount] = b[i] + b[j];
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+ }
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+}
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+
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+// sort c, with time complexity n squared log (n squared), which reduces to n squared log n
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+std::sort(c, c + clen);
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+
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+// for reach sum in a, see if it is in c. n squared checks of log (n squared), or n squared log n
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+for (int i = 0; i < clen; ++i)
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+{
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+ for (int j = (i + 1); j < n; ++j)
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+ {
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+ if (std::binary_search(c, c + clen), (a[i] + a[j]))
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+ {
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+ free(a); free (b); free(c);
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+ cout << 1 << endl;
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+ return true;
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+ }
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+ }
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+}
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+
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+free(a); free(b); free(c);
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+cout << 0 << endl;
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+return false;
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+
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