Jump Game II Problem Solution

Jump Game II Problem: Given an array of non-negative integers nums, you are initially positioned at the first index of the array.

Each element in the array represents your maximum jump length at that position.

Your goal is to reach the last index in the minimum number of jumps.

You can assume that you can always reach the last index.

Example :

Input: nums = [2,3,1,1,4]
Output: 2
Explanation: The minimum number of jumps to reach the last index is 2. Jump 1 step from index 0 to 1, then 3 steps to the last index.

Jump Game II Problem Solution

Problem Solution In Python

class Solution(object):
def jump(self, nums):
    res = 0
    edge = 0
    maxEdge = 0
    for i in range(len(nums)):
        if i > edge:
            edge = maxEdge
            res += 1
        maxEdge = max(maxEdge,i+nums[i])
    return res

Problem Solution In Java

class Solution {
    public int jump(int[] nums) {
         int ladder = 0;
         int stair = 1;
         int jump = 0;
 
         for (int level = 0; level < nums.length; level++) {
             if (level == nums.length - 1) {
                 return jump;
             }
             if (nums[level] + level >= ladder)
                 ladder = nums[level] + level;
 
             stair--;
 
             if (stair == 0) {
                 jump++;
                 stair = ladder - level;
                 if (stair == 0)
                     return -1;
             }
         }
         return jump;
    }
}

Problem Solution In C++

class Solution {
public:
    int jump(vector<int>& nums) {
        int jumps = 0 , limit = 0 , next_limit = 0;
        for(int i = 0;i < nums.size()-1;i++){
            next_limit = max(next_limit,i+nums[i]);
            if(i == limit){
                jumps++;
                limit = next_limit;
            }
        }
        return jumps;
    }
};

Problem Solution In C

int jump(int* n, int ns){
    if(ns <= 1) return 0;
    int r = n[0];
    if(r >= ns - 1) return 1;
    int max = r + n[r];
    int maxid = r;
    for(int i = 1; i <= r; i++)
        if(n[i] + i > max)
            max = n[i] + i, maxid = i;
    return jump(&n[maxid], ns - maxid) + 1;
}

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