Day33 ＞＞ 509、斐波那契数 + 70、爬楼梯 + 746、使用最小花费爬楼梯

代码随想录-动态规划

509、斐波那契数

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

70、爬楼梯

class Solution { public int climbStairs(int n) { if (n <= 2) { return n; } int result = 0; int[] dp = new int[n + 1]; dp[1] = 1; dp[2] = 2; for (int i = 3; i <= n; i++) { dp[i] = dp[i - 1] + dp[i - 2]; } result = dp[n]; return result; } }

746、使用最小花费爬楼梯

class Solution { public int minCostClimbingStairs(int[] cost) { int[] dp = new int[cost.length + 1]; dp[0] = 0; dp[1] = 0; for (int i = 2; i <= cost.length; i++) { dp[i] = Math.min(dp[i-1]+cost[i-1], dp[i-2]+cost[i-2]); } return dp[cost.length]; } }