1
var numberOfWeakCharacters = function (properties) {
2
  // sort strongest to weakest
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  properties.sort((a, b) => {
4
    if (b[0] - a[0]) {
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      return b[0] - a[0];
6
    }
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    return b[1] - a[1];
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  });
9

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  // map all the unique index 0 values to a (descending)
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  // sorted array
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  const uniqueZeroIndexToOneIndex = new Map();
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  for (const [a, b] of properties) {
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    if (!uniqueZeroIndexToOneIndex.has(a)) {
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      uniqueZeroIndexToOneIndex.set(a, []);
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    }
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    uniqueZeroIndexToOneIndex.get(a).push(b);
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  }
19

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  // get all the unique index 0 values
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  const nums = [...uniqueZeroIndexToOneIndex.keys()];
22

23
  let maxValue = -1;
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  let numWeakCharacters = 0;
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  for (let i = 0; i < nums.length; i++) {
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    // skip key in case if we deleted the key
27
    if (!uniqueZeroIndexToOneIndex.has(nums[i])) continue;
28

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    const maxValOfI = uniqueZeroIndexToOneIndex.get(nums[i])[0];
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    if (maxValOfI <= maxValue) continue;
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    maxValue = maxValOfI;
32

33
    for (let j = i + 1; j < nums.length; j++) {
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      // skip key in case if we deleted the key
35
      if (!uniqueZeroIndexToOneIndex.has(nums[j])) continue;
36

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      // valuesOfJ will be sorted in descending order
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      const valuesOfJ = uniqueZeroIndexToOneIndex.get(nums[j]);
39

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      // pop off all the weak values and add to numWeakCharacters
41
      for (let k = valuesOfJ.length - 1; k >= 0; k--) {
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        if (maxValue > valuesOfJ[k]) {
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          valuesOfJ.pop();
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          numWeakCharacters++;
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        } else {
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          // we won't be able to find any more weak characters
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          // in valuesOfJ
48
          break;
49
        }
50
      }
51
      if (valuesOfJ.length === 0) {
52
        // delete the key if all the values were weak characters
53
        uniqueZeroIndexToOneIndex.delete(nums[j]);
54
      } else {
55
        // if there is a stronger character updated it so we can
56
        // eliminate more characters
57
        maxValue = Math.max(valuesOfJ[0], maxValue);
58
      }
59
    }
60
  }
61
  return numWeakCharacters;
62
};