// 1237. Find Positive Integer Solution for a Given Equation #include "leetcode.h" /* * given a callable function 'f(x, y)' with a hidden formula and a value 'z', * reverse engineer the formula and return all positive integer pairs 'x' and * 'y' where 'f(x, y) == z'. you may return the pairs in any order. while the * exact formula is hidden, the function is monotonically increasing. */ int function_id = 0; int customFunction(int x, int y) { switch (function_id) { case 1: return x + y; case 2: return x * y; } } int **findSolution(int (*customFunction)(int, int), int z, int *returnSize, int **returnColumnSizes) { int **ans = (int **)malloc(z * sizeof(int *)), k = 0; int *cols = *returnColumnSizes = (int *)malloc(z * sizeof(int)); for (int i = 1; i <= z; i++) for (int j = z; j >= 1; j--) if (customFunction(i, j) == z) { (ans[k] = (int *)malloc(sizeof(int[cols[k] = 2])))[0] = i; ans[k++][1] = j; } *returnSize = k; return ans; } int main() { function_id = 1; int rs1, *rcs1, **fs1 = findSolution(customFunction, 5, &rs1, &rcs1); for (int i = 0; i < rs1; i++) { for (int j = 0; j < rcs1[i]; j++) printf("%d ", fs1[i][j]); // expect: [[1,4],[2,3],[3,2],[4,1]] printf("\n"); } function_id = 2; int rs2, *rcs2, **fs2 = findSolution(customFunction, 5, &rs2, &rcs2); for (int i = 0; i < rs2; i++) { for (int j = 0; j < rcs2[i]; j++) printf("%d ", fs2[i][j]); // expect: [[1,5],[5,1]] printf("\n"); } for (int i = 0; i < rs1; i++) free(fs1[i]); free(rcs1); free(fs1); for (int i = 0; i < rs2; i++) free(fs2[i]); free(rcs2); free(fs2); }