vector<int> diffWaysToCompute2(vector<int>& nums,int beg,int end,vector<char>& opts) {
vector<int> ans;
if(beg==end){
ans.push_back(nums[beg]);
return ans;
}
for(int j=beg;j<end;j++){
vector<int> a=diffWaysToCompute2(nums,beg,j,opts);
vector<int> b=diffWaysToCompute2(nums,j+1,end,opts);
for(int x=0;x<a.size();x++){
for(int y=0;y<b.size();y++){
switch(opts[j]){
case '+':
ans.push_back(a[x]+b[y]);
break;
case '-':
ans.push_back(a[x]-b[y]);
break;
case '*':
ans.push_back(a[x]*b[y]);
break;
}
}
}
}
return ans;
}
int* diffWaysToCompute(char* input, int* returnSize) {
IntArray operands = int_array();
IntArray operators = int_array();
int count = 0;
/* normalize the string into operands and operators */
normalize(input, &operands, &operators, &count);
/* use the normalized data to compute */
int* result = diffWaysToCompute2(&operands, &operators, count, 0, returnSize);
int_array_free(&operands);
int_array_free(&operators);
return result;
}
vector<int> diffWaysToCompute(string input) {
vector<int> nums;
vector<int> ans;
vector<char> opts;
int i=0;
while(1){
int n=0;
while(i<input.size()&&isdigit(input[i])){
n=n*10+input[i]-'0';
i++;
}
nums.push_back(n);
if(i==input.size()){
break;
}
opts.push_back(input[i++]);
}
ans=diffWaysToCompute2(nums,0,nums.size()-1,opts);
return ans;
}
int* diffWaysToCompute2(IntArray* operands, IntArray* operators, int size,
int pos, int* returnSize) {
int count = 0;
IntArray result = int_array();
if (size == 0) {
/* single operator */
int_array_set(&result, count++, operands->array[0]);
} else {
/* recursion, add parenthese at each operator position */
for (int i = pos; i < size; ++i) {
int op = operators->array[i];
int lv = operands->array[i];
int rv = operands->array[i + 1];
int value = 0;
if (op == '+') {
value = lv + rv;
} else if (op == '-') {
value = lv - rv;
} else {
value = lv * rv;
}
IntArray new_operands = int_array_rm(operands, size + 1, i);
IntArray new_operators = int_array_rm(operators, size, i);
int_array_set(&new_operands, i, value);
int sub_size;
int* sub = diffWaysToCompute2(&new_operands, &new_operators, size - 1,
i == 0 ? 0 : i - 1, &sub_size);
for (int j = 0; j < sub_size; ++j) {
int_array_set(&result, count++, sub[j]);
}
free(sub);
}
}
*returnSize = count;
return result.array;
}