Jump Game Program

Overview

There is an input array provided. Each entry in the array represents the maximum jump length from that position. One is supposed to start from the first index and return true if the last index can be reached and return false if the last index cannot be reached

Example

Input: [2, 3, 1, 1, 4]
Output: true

Input: [3, 2, 1, 0, 4]
Output: false

In the first example, there are different ways to reach the last index.

• 0-1-4

• 0-2-3-4

In the second example, there is no way to reach the last index. The best you can reach is the second last index. Since the value at the second last index is zero, therefore it is not possible to reach the last index.

There is another variation where you have to return the minimum number of jumps. We will look at the program later

Program

package main

import "fmt"

func canJump(nums []int) bool {
	lenNums := len(nums)
	canJumpB := make([]bool, lenNums)

	canJumpB[0] = true

	for i := 0; i < lenNums; i++ {

		if canJumpB[i] {
			valAtCurrIndex := nums[i]
			for k := 1; k <= valAtCurrIndex && i+k < lenNums; k++ {
				canJumpB[i+k] = true
			}
		}

	}

	return canJumpB[lenNums-1]
}

func main() {
	input := []int{2, 3, 1, 1, 4}

	canJumpOrNot := canJump(input)
	fmt.Println(canJumpOrNot)

	input = []int{3, 2, 1, 0, 4}

	canJumpOrNot = canJump(input)
	fmt.Println(canJumpOrNot)

}

Output

true
false

There is another variation where you have to return the minimum number of jumps. Here is the program for the same

package main

import "fmt"

func jump(nums []int) int {

	lenJump := len(nums)
	minJumps := make([]int, lenJump)
	for i := 0; i < lenJump; i++ {
		minJumps[i] = -1
	}

	minJumps[0] = 0

	for i := 0; i < lenJump; i++ {
		currVal := nums[i]

		for j := 1; j <= currVal && i+j < lenJump; j++ {
			if minJumps[i+j] == -1 || minJumps[i+j] > minJumps[i]+1 {
				minJumps[i+j] = minJumps[i] + 1
			}
		}
	}

	return minJumps[lenJump-1]

}

func main() {
	input := []int{2, 3, 1, 1, 4}

	minJump := jump(input)
	fmt.Println(minJump)

	input = []int{3, 2, 1, 0, 4}

	minJump = jump(input)
	fmt.Println(minJump)

}

Output

2
-1