Minimum Number of K Consecutive Bit Flips LeetCode solution in C++

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class Solution {
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 public:
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  int minKBitFlips(vector<int> &nums, int k) {
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    int n = nums.size();
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    int flips = 0;              // flips on current positions
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    vector<int> flip(n + 1, 0); // to set end pointer for a flip i.e i+k ->-1
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    int ops = 0;                // answer
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    for (int i = 0; i < n; i++) {
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      flips += flip[i]; // update flips for current position
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      // even flips on 1 okay
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      if (nums[i] == 1 && (flips) % 2 == 0) {
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        continue;
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      }
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      // odd flips on 0 okay
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      if (nums[i] == 0 && (flips) % 2 != 0) {
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        continue;
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      }
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      // margin error as k bits flips is must
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      if (i + k > n) {
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        return -1;
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      }
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      ops++;            // increment ans
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      flips++;          // do flip at this position
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      flip[i + k] = -1; // set poiter where current flip ends
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    }
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    return ops;
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  }
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};