题解 | #不相邻取数#

#include<iostream>
using namespace std;
int dp[100000];
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    int n;
    bool ans = true;
    cin >> n;
    int* num = new int[n];
    for (int i = 0; i < n; ++i) {
        cin >> num[i];
        dp[i] = 0;
    }
    dp[0] = num[0];
    for (int i = 0; i < n; ++i) {
        for (int j = i + 1; dp[i] && j <= i + num[i] && j < n; ++j) {
            dp[j] = max(dp[j], dp[i] + num[j]);
        }
    }
    if (dp[n - 1] == 0)
        cout << -1;
    else
        cout << dp[n - 1];
}