240521 창고 다각형

public static void main(String[] args) throws IOException {
	BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	
	int n = Integer.parseInt(br.readLine());
	int[] heights = new int[1001];
	int start = Integer.MAX_VALUE;
	int end = 0;

	for (int i = 0; i < n; i++) {
		StringTokenizer st = new StringTokenizer(br.readLine());
		int l = Integer.parseInt(st.nextToken());
		int h = Integer.parseInt(st.nextToken());
		heights[l] = h;
		start = Math.min(start, l);
		end = Math.max(end, l);
	}

	int maxIdx = findMaxHeightIndex(heights, start, end);
	int totalArea = calculateArea(heights, start, end, maxIdx);

	System.out.println(totalArea);
}

private static int findMaxHeightIndex(int[] heights, int start, int end) {
	int max = 0;
	int maxIdx = 0;
	for (int i = start; i <= end; i++) {
		if (heights[i] > max) {
			max = heights[i];
			maxIdx = i;
		}
	}
	return maxIdx;
}

private static int calculateArea(int[] heights, int start, int end, int maxIdx) {
	int totalArea = 0;

	int curHeight = 0;
	for (int i = start; i < maxIdx; i++) {
		curHeight = Math.max(curHeight, heights[i]);
		totalArea += curHeight;
	}

	curHeight = 0;
	for (int i = end; i > maxIdx; i--) {
		curHeight = Math.max(curHeight, heights[i]);
		totalArea += curHeight;
	}

	totalArea += heights[maxIdx];
	return totalArea;
}

출처:https://www.acmicpc.net/problem/2304