1
var rectangleArea = function (rectangles) {
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  let events = [],
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    active = [],
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    area = 0n;
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  let mod = BigInt(1000000007);
6

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  for (var rec of rectangles) {
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    events.push([rec[1], "open", rec[0], rec[2]]);
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    events.push([rec[3], "close", rec[0], rec[2]]);
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  }
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  events = events.sort((a, b) => a[0] - b[0]);
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  let y = events[0][0];
14

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  for (var event of events) {
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    let currY = event[0],
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      type = event[1],
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      x1 = event[2],
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      x2 = event[3];
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    let maxLength = 0,
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      curr = -1;
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    for (var ev of active) {
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      curr = Math.max(curr, ev[0]);
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      maxLength += Math.max(0, ev[1] - curr);
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      curr = Math.max(curr, ev[1]);
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    }
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    area += BigInt(maxLength) * BigInt(currY - y);
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    area %= mod;
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    if (type === "open") {
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      active.push([x1, x2]);
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      active = active.sort((a, b) => a[0] - b[0]);
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    } else {
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      for (var i = 0; i < active.length; i++) {
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        let e = active[i];
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        if (e[0] === x1 && e[1] === x2) {
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          active.splice(i, 1);
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          break;
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        }
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      }
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    }
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    y = currY;
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  }
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  return area % mod;
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};