백준 - 빗물 [14719]

#include <iostream>

using namespace std;


int main() {
	int c, r;
	int arr[500];
	int temp;
	int curr = 0;
	int result = 0;
	cin >> c >> r;
	for (int i = 0; i < r; i++)
		cin >> arr[i];
	temp = arr[0];
	for (int i = 0; i < r; i++) {
		if (temp <= arr[i]) {
			for (int j = curr; j < i; j++)
				result += temp - arr[j];
			temp = arr[i];
			curr = i;
		}
	}
	temp = arr[r-1];
	curr = r - 1;
	for (int i = r-1; i >= 0 ; i--) {
		if (temp < arr[i]) {
			for (int j = curr; j > i; j--)
				result += temp - arr[j];
			temp = arr[i];
			curr = i;
		}
	}

	cout << result;
	return 0;
}