<p>Given a collection of candidate numbers (<code>candidates</code>) and a target number (<code>target</code>), find all unique combinations in <code>candidates</code>&nbsp;where the candidate numbers sum to <code>target</code>.</p>

<p>Each number in <code>candidates</code>&nbsp;may only be used <strong>once</strong> in the combination.</p>

<p><strong>Note:</strong>&nbsp;The solution set must not contain duplicate combinations.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> candidates = [10,1,2,7,6,1,5], target = 8
<strong>Output:</strong> 
[
[1,1,6],
[1,2,5],
[1,7],
[2,6]
]
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> candidates = [2,5,2,1,2], target = 5
<strong>Output:</strong> 
[
[1,2,2],
[5]
]
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;=&nbsp;candidates.length &lt;= 100</code></li>
	<li><code>1 &lt;=&nbsp;candidates[i] &lt;= 50</code></li>
	<li><code>1 &lt;= target &lt;= 30</code></li>
</ul>

class Solution {
public:
    vector<vector<int>> dp[103][31];
    int dp_v[103][31];
    vector<vector<int>> solve(vector<pair<int, int>>& v, int idx, int target) {
        vector<vector<int>> ret;
        if (target == 0) {
            ret = {{}};
            return ret;
        }
        else if (idx == v.size() || target < 0) {
            return ret;
        }
        if (dp_v[idx][target] != 0) {
            return dp[idx][target];
        }
        else {
            ret = solve(v, idx+1, target);
            vector<vector<int>> rslt;
            for (int i = 0; i < v[idx].second; i++) {
                rslt = solve(v, idx+1, target-(i + 1) * v[idx].first);
                for (int j = 0; j <= i; j++) {
                    for (auto& vv : rslt) {
                        vv.push_back(v[idx].first);
                    }
                }
                ret.insert(ret.end(), rslt.begin(), rslt.end());
            }
        }
        dp_v[idx][target]=1;
        dp[idx][target] = ret;
        return ret;
    }
    vector<vector<int>> combinationSum2(vector<int>& candidates, int target) {
        sort(candidates.begin(), candidates.end());
        vector<pair<int, int>> v;
        vector<vector<int>> ret;
        for (int i = 0; i < candidates.size(); i++) {
            if (candidates[i] > target) {
                break;
            }
            int count = 0;
            while (i + count < candidates.size() && candidates[i + count] == candidates[i]) {
                count++;
            }
            i += count;
            i--;
            v.push_back({candidates[i], count});
        }
        return solve(v, 0, target);
    }
};
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