ProjectEuler Problem 18.Maximum path sum I

题目链接：18.Maximum path sum I

题意：

   By starting at the top of the triangle below and moving to adjacent numbers on the row below, the maximum total from top to bottom is 23.

3
7 4
2 4 6
8 5 9 3

That is, 3 + 7 + 4 + 9 = 23.

 

解题思路：

   动态规划的思想，下一行的值等于上一行和他相邻的两个值的最大值，加上当前值

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int maxn = 25;
int a[maxn][maxn];
int main() {
	int n, ans = 0;
	cin >> n;
	for(int i = 1; i <= n; i++) {
		for(int j = 1; j <= i; j++) {
			cin >> a[i][j];
		}
	}
	for(int i = 2; i <= n; i++) {
		for(int j = 1; j <= i; j++) {
			a[i][j] += max(a[i-1][j-1], a[i-1][j]);
			ans = max(ans, a[i][j]);
		}
	}
	cout << ans << endl;
	return 0;
}