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// 241. Different Ways to Add Parentheses
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
/*
* 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
}
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