45. Jump Game II

https://leetcode.com/problems/jump-game-ii/description/

class Solution {
public:
    int jump(vector<int>& nums) {
        int n = nums.size();
        if (n <= 1) return 0;
        vector<int> dp(n, 0);
        for (int i = 0; i < n; i++) {
            if (i + nums[i] >= n-1)
                return dp[i] + 1;
            for (int j = i + nums[i]; j >= i && dp[j] == 0; j--)
                dp[j] = dp[i] + 1;
        }
        return -1;
        /*
        int n = nums.size();
        if (n <= 1) return 0;
        vector<int> dp(n, n);
        dp[0] = 0;
        for (int i = 1; i < n; i++) {
            for (int j = 0; j < i; j++) {
                if (j + nums[j] >= i)
                    dp[i] = min(dp[i], dp[j] + 1);
            }
        }
        return dp[n-1];
        */
    }
};