代码随想录算法训练营Day48|贪心算法7
文章目录
一、70. 爬楼梯
class Solution {
public int climbStairs(int n) {
int[] dp = new int[n + 1];
int m = 2;
dp[0] = 1;
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= m; j++) {
if (i >= j)
dp[i] += dp[i - j];
}
}
return dp[n];
}
}
二、322. 零钱兑换
class Solution {
public int coinChange(int[] coins, int amount) {
int max = Integer.MAX_VALUE;
int[] dp = new int[amount + 1];
for (int j = 0; j < dp.length; j++) {
dp[j] = max;
}
dp[0] = 0;
for (int i = 0; i < coins.length; i++) {
for (int j = coins[i]; j <= amount; j++) {
if (dp[j - coins[i]] != max) {
dp[j] = Math.min(dp[j], dp[j - coins[i]] + 1);
}
}
}
return dp[amount] == max ? -1 : dp[amount];
}
}
三、279. 完全平方数
class Solution {
public int numSquares(int n) {
int max = Integer.MAX_VALUE;
int[] dp = new int[n + 1];
for (int j = 0; j <= n; j++) {
dp[j] = max;
}
dp[0] = 0;
for (int j = 1; j <= n; j++) {
for (int i = 1; i * i <= j; i++) {
dp[j] = Math.min(dp[j], dp[j - i * i] + 1);
}
}
return dp[n];
}
}