动态规划

198. 打家劫舍

class Solution {
    public int rob(int[] nums) {
        if(nums == null || nums.length == 0) return 0;
        int length = nums.length;
        if(length == 1) return nums[0];

        int[] dp = new int[length];
        dp[0] = nums[0];
        dp[1] = Math.max(nums[0], nums[1]);
        for(int i  = 2; i < length; i++){
            dp[i] = Math.max(dp[i-2] + nums[i], dp[i-1]);
        }
        return dp[length-1];
    }
}

70. 爬楼梯

class Solution {
    public int climbStairs(int n) {
        int[] dp = new int[n + 1];
        dp[0] = 1;
        dp[1] = 1;
        for(int i = 2; i <= n; i++) {
            dp[i] = dp[i - 1] + dp[i - 2];
        }
        return dp[n];
    }
}