C++题解

#include <bits/stdc++.h>
#define ll long long
using namespace std;

const int N = 209;
int n, A, B, K[N], ans = -1;
bool vis[N];

void dfs (int x, int step) {
	if (x == B) {
		if(ans == -1) {
			ans = step;
		} else {
			ans = min(ans, step);
		}
	}
	
	if (ans != -1 && step > ans) {
		return;
	}
	
	if(x + K[x] <= N && !vis[x+K[x]]) {
		vis[x + K[x]] = 1;
		dfs(x + K[x], step + 1);
		vis[x + K[x]] = 0;
	}
	if(x - K[x] >= 1 && !vis[x-K[x]]) {
		vis[x - K[x]] = 1;
		dfs(x - K[x], step + 1);
		vis[x - K[x]] = 0;
	}
	
	return;
}

int main() {
	cin >> n >> A >> B;
	for(int i = 1; i <= N; ++i) {
		cin >> K[i];
	}
	
	dfs(A, 0);
	
	cout << ans;
	
	return 0;
}