package array;

class Lt42 {

// 투포인터

public int trap(int[] height) {

int left = 0, right = height.length -1;

int leftMax = 0, rightMax = 0;

int water = 0;

while (left < right) {

if (height[left] < height[right]) {

if (height[left] >= leftMax) {

leftMax = height[left];

} else {

water += leftMax - height[left];

}

left++;

} else {

if (height[right] >= rightMax) {

rightMax = height[right];

} else {

water += rightMax - height[right];

}

right--;

}

}

return water;

}

}