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class Solution {
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 public:
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  vector<int> threeEqualParts(vector<int> &v) {
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    vector<int> one;
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    int n = v.size();
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    for (int i = 0; i < n; i++) {
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      if (v[i] == 1) one.push_back(i + 1);
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    }
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    if (one.size() == 0) {
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      return {0, 2};
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    }
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    if (one.size() % 3) return {-1, -1};
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    int ext = n - one.back(), sz = one.size();
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    int gap1 = one[sz / 3] - one[sz / 3 - 1] - 1, gap2 = one[2 * sz / 3] - one[2 * sz / 3 - 1] - 1;
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    // cout<<gap1<<" "<<gap2<<endl;
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    if (gap1 < ext || gap2 < ext) return {-1, -1};
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    string s1, s2, s3;
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    for (int i = 0; i <= one[sz / 3 - 1] + ext - 1; i++) {
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      if (s1.length() > 0 || v[i]) s1 += to_string(v[i]);
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    }
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    for (int i = one[sz / 3 - 1] + ext; i <= one[2 * sz / 3 - 1] + ext - 1; i++) {
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      if (s2.length() > 0 || v[i]) s2 += to_string(v[i]);
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    }
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    for (int i = one[2 * sz / 3 - 1] + ext; i <= n - 1; i++) {
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      if (s3.length() > 0 || v[i]) s3 += to_string(v[i]);
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    }
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    // All 3 Numbers in vector v :-
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    //  num1={0,one[sz/3-1]+ext-1};
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    //  num2={one[sz/3-1]+ext,one[2*sz/3-1]+ext-1}
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    //  num3={one[2*sz/3-1]+ext,n-1};
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    if (s1 == s2 && s2 == s3) return {one[sz / 3 - 1] + ext - 1, one[2 * sz / 3 - 1] + ext};
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    return {-1, -1};
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  }
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};