// 241. Different Ways to Add Parentheses #include #include #include /* * given a string 'expression' of numbers and operators, return all possible * results from computing all the different possible ways to group numbers and * operators. you may return the answer in any order. the test cases are * generated such that the output values fit in a 32-bit integer and the number * of different results is <10^4 */ #define CAL(a, b, op) ('+' == op ? a + b : '-' == op ? a - b : a * b) void token_size(char *s, char **op, int **num, int *return_size) { int i, s_len = (int)strlen(s), len = 0; int *res = malloc(sizeof(int) * ((s_len + 1) >> 1)); char *ops = malloc(s_len >> 1); res[0] = 0; for (int i = 0; i < s_len; ++i) { if ('0' > s[i] || s[i] > '9') { ops[len++] = s[i]; res[len] = 0; } else res[len] = res[len] * 10 + s[i] - '0'; } len++; *return_size = len; *num = res; *op = ops; } int *helper(int *return_size, int *nums, int len, char *op) { int i, j, k, cnt = 0, cap = 10, *set = malloc(sizeof(int) * cap); int *ss1 = NULL, *ss2 = NULL, sl1 = 0, sl2 = 0; if (2 >= len) { set[cnt++] = 1 == len ? nums[0] : CAL(nums[0], nums[1], op[0]); *return_size = cnt; return set; } for (i = 1; i <= len - 1; ++i) { ss1 = helper(&sl1, nums, i, op); ss2 = helper(&sl2, nums + i, len - i, op + i); if (cnt + sl1 * sl2 >= cap) { cap += (sl1 * sl2) << 1; set = realloc(set, sizeof(int) * cap); } for (j = 0; j < sl1; ++j) for (k = 0; k < sl2; ++k) set[cnt++] = CAL(ss1[j], ss2[k], op[i - 1]); free(ss1); free(ss2); } *return_size = cnt; return set; } int *diffWaysToCompute(char *expression, int *return_size) { int *nums, *ans, len; char *op; if (!expression) { *return_size = 0; return NULL; } token_size(expression, &op, &nums, &len); ans = helper(return_size, nums, len, op); free(op); free(nums); return ans; } int main() { char e1[] = {"2 - 1 - 1"}, e2[] = {"2 * 3 - 4 * 5"}; int *dwtc1 = diffWaysToCompute(e1, NULL); int *dwtc2 = diffWaysToCompute(e2, NULL); for (int i = 0; i < 2; i++) printf("%d ", dwtc1[i]); // expect: 0,2 printf("\n"); for (int i = 0; i < 5; i++) printf("%d ", dwtc2[i]); // expect: -34,-14,-10,-10,10 }