Leetcode/src/DifferentWaystoAddParentheses/program.cpp at master · robling/Leetcode · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
#include "../include/pre.h"
#include <set>
#include <tuple>
#include <list>
#include <sstream>

template<typename ForwardIterator>
vector<typename ForwardIterator::value_type> subVector(ForwardIterator it_start, ForwardIterator it_end)
{
    vector<typename ForwardIterator::value_type> rst;
    while(it_start != it_end) rst.push_back(*it_start++);
    return rst;
}

std::tuple<std::vector<int>, std::vector<char>> parser(string& input)
{
    std::vector<int> nums;
    std::vector<char> ops;
    std::stringstream ss(input);
    int k;
    ss >> k;
    nums.push_back(k);
    while(!ss.eof())
    {
        int i;
        char ch;
        ss >> ch;
        ss >> i;
        ops.push_back(ch);
        nums.push_back(i);
    }
    return std::tie(nums, ops);
}
int solve(int a, int b, char op)
{
    switch(op){
    case '-':
        return a - b;
    case '+':
        return a + b;
    case '*':
        return a * b;
    default:
        assert(false);
        return 0;
    }
}

namespace allPossibleEvaluation{
template<typename _T>
vector<_T> without(const vector<_T>& input, size_t n)
{
    vector<_T> rst;
    rst.reserve(input.size() - 1);
    for (size_t i = 0; i != input.size(); i++)
    {
        if (i != n) rst.push_back(input[i]);
    }
    return rst;
}

void diffWaysToCompute_helper(std::vector<int>& nums, std::vector<char>& ops, std::set<int>& rst)
{
    if (ops.size() == 0) {
        rst.insert(nums[0]);
        return;
    }
    for (int i = 0; i != ops.size(); i++) {
        auto k = solve(nums[i], nums[i + 1], ops[i]);
        auto nextNums = without(nums, i);
        nextNums[i] = k;
        diffWaysToCompute_helper(nextNums, without(ops, i), rst);
    }
}

vector<int> diffWaysToCompute(string input)
{
    std::set<int> rst;
    auto data = parser(input);
    diffWaysToCompute_helper(std::get<0>(data), std::get<1>(data), rst);
    vector<int> rst_;
    for (auto i : rst)
    {
        rst_.push_back(i);
    }
    return rst_;
}
} //namespace

vector<int> helper (const vector<int> & nums, const vector<char> & ops)
{
    if (ops.size() == 0) return { nums };
    if (ops.size() == 1) return { solve(nums[0], nums[1], ops[0]) };
    vector<int> rst;
    for (size_t i = 0; i != ops.size(); i++) {
        auto sub1 = helper(
            subVector(nums.begin(), nums.begin() + i + 1),
            subVector(ops.begin(), ops.begin() + i)
        );
        auto sub2 = helper(
            subVector(nums.begin() + i + 1, nums.end()),
            subVector(ops.begin() + i + 1, ops.end())
        );
        for (auto s1 : sub1) {
            for (auto s2 : sub2) {
                rst.push_back(solve(s1, s2, ops[i]));
            }
        }
    }
    return rst;
}

vector<int> diffWaysToCompute(string input)
{
    vector<int> nums;
    vector<char> ops;
    std::tie(nums, ops) = parser(input);
    return helper(nums, ops);
}

int main()
{
    using namespace std;
    vector<string> tests = {
        "2*3-4*5",
        "2-1-1",
        };
    for (auto& s : tests)
    {
        cout << "A:" << diffWaysToCompute(s) << endl;
    }
    return 0;
}