leetcode跳跃数字

解法1:：贪心（推荐）

class Solution {
    public boolean canJump(int[] nums) {
        int ans = 0;
        for(int i = 0;i<nums.length-1;i++){
            ans = Math.max(ans,nums[i]+i);
            if(ans<=i){
                return false;
            }
        }
        return true;
    }

}

解法2：递归

public boolean flag=false;
    public int[] vis;
    public void dfs(int[]nums,int index,int step){
        if(flag){
            return;
        }
        if(vis[index]==1||vis[index]==-1){
            return;
        }
        if(index==nums.length-1){
            flag = true;
            return;
        }
        for(int i = index+step;i>index;i--){
            if(i>=nums.length){
                continue;
            }
            dfs(nums,i,nums[i]);
        }
        vis[index]=flag?1:-1;
    }
    public boolean canJump(int[] nums) {
        if(0==nums.length){
            return false;
        }
        vis = new int[nums.length];
        dfs(nums,0,nums[0]);
        return flag;
    }