const elevationArray = [0, 1, 0, 2, 1, 0, 3, 1, 0, 1, 2]

const getTrappedRainwater = function(heights) {
  let totalWater = 0;
  
  for(let p = 0; p < heights.length; p++) {
    let leftP = p, rightP = p, maxLeft = 0, maxRight = 0; 

    while(leftP >= 0) {
      maxLeft = Math.max(maxLeft, heights[leftP]);
      leftP--;
    }

    while(rightP < heights.length) {
      maxRight = Math.max(maxRight, heights[rightP]);
      rightP++;
    }
    
    const currentWater = Math.min(maxLeft, maxRight) - heights[p];
    
    if(currentWater >= 0) {
      totalWater += currentWater;
    }
  }

  return totalWater;
}

console.log(getTrappedRainwater(elevationArray));