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题目链接
思路:dp[i] = dp[i - 1] + dp[i - 2],从前向后
class Solution {
public int fib(int n) {
if (n < 2) return n;
int a = 0, b = 1, c = 0;
for (int i = 2; i <= n; i++) {
c = a + b;
a = b;
b = c;
}
return c;
}
}
题目链接
思路:1楼有1种方法,2楼有两种方法,上3楼只需要在1楼的基础上走2步,在2楼的基础上走1步,所以3楼的方法就等于1楼的方法加2楼的方法,dp[i] = dp[i-1]+dp[i-2]
class Solution {
public int climbStairs(int n) {
if (n < 3) return n;
int a = 1, b = 2, c = 0;
for (int i = 3; i <= n ; i++) {
c = a + b;
a = b;
b = c;
}
return c;
}
}
题目链接
思路:
class Solution {
public int minCostClimbingStairs(int[] cost) {
int a = 0, b = 0;
for (int i = 2; i <= cost.length; i++) {
int c = Math.min(a+cost[i-2], b+cost[i-1]);
a = b;
b = c;
}
return b;
}
}
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