LeetCode - Jump Game II

JumpGameII.java

public int jump(int[] A) {
        // write your code here
        int reach = 0, step = 0, max = 0;
        for(int i=0; i<=reach; i++){
            if(reach >= A.length-1) return step;
            max = Math.max(max, A[i]+i);
            if(i == reach){
                reach = max;
                step++;
            }
        }
        return -1;
    }

// this solution may cause infinite loop test case: {1, 0, 0 ,0}
public int jump(int[] A) {
        if(A==null || A.length==0) return 0;
        int max=0, temp=0, i=0, num=0;
        while(i<A.length){
            if(temp>=A.length-1) break;
            while(i<=temp){
                max = Math.max(i+A[i], max);
                i++;
            }
            num++;
            temp = max;
        }
        return num;
    }
    
//
public int jump(int[] nums) {
        if(nums == null || nums.length == 0) return 0;
        int reach = 0, jump = 0;
        for(int i=0; i <= reach;){
            if(reach >= nums.length -1) return jump;
            int localMax = 0;
            while(i <= reach){
                localMax = Math.max(localMax, i + nums[i]);
                i++;
            }
            reach = localMax;
            jump++;
        }
        return -1;
}