袋鼠过河

一只袋鼠要从河这边跳到河对岸，河很宽，但是河中间打了很多柱子，略去。

这道题做完感觉也是原题，上周leetcode周赛的frog jump，前面还有几道jump的题，可以在leetcode上面搜索关键字jump。

frog jump题解链接http://www.cnblogs.com/y119777/p/5882697.html

这道题想清楚是一次只能跳这么多，还是可以这个区间随便跳，然后思路就很清楚。

#include<bits/stdc++.h>
#define pb push_back
#define FOR(i, n) for (int i = 0; i < (int)n; ++i)
#define dbg(x) cout << #x << " at line " << __LINE__ << " is: " << x << endl
typedef long long ll;
using namespace std;
typedef pair<int, int> pii;
const int maxn = 1e3 + 10;
void solve() {
    int n;
    cin >> n;
    vector<int> a(n + 1, 0), cnt(n + 1, -1);
    for (int i = 0; i < n; i++) cin >> a[i];
    int cur = 0;
    int step = 0;
    int left, right;
    left = right = 0;
    while(1) {
        int r = right;
        for (int i = left; i <= right; i++) {
            r = max(r, i + a[i]);
        }
        left = right + 1, right = r;
        step ++;
        if(left <= right && right >= n) {
            cout << step << endl; return;
        }
        if(right < left) {
            cout << -1 << endl; return;
        }
    }

}
int main() {
    //freopen("test.in", "r", stdin);
    //freopen("test.out", "w", stdout);
    solve();
    return 0;
}