package org.example.interview.practice; import java.util.Arrays; /** * @author xianzhe.ma * @date 2021/8/16 */ public class NC_126_MIN_MONEY { public int minMoney (int[] arr, int aim) { // write code here int Max = aim + 1;//定一个全局最大值 int []dp = new int[aim + 1];//dp[i]的含义是目标值为i的时候最少钱币数是多少。 Arrays.fill(dp,Max);//把dp数组全部定为最大值 dp[0] = 0;//总金额为0的时候所需钱币数一定是0 for(int i = 1;i <= aim;i ++){// 遍历目标值 for(int j = 0;j < arr.length;j ++){// 遍历钱币 if(arr[j] <= i){//如果当前的钱币比目标值小就可以兑换 dp[i] = Math.min(dp[i],dp[i-arr[j]] + 1); } } } return dp[aim] > aim ? -1 : dp[aim]; } }
package org.example.interview.practice; /** * @author xianzhe.ma * @date 2021/9/2 */ public class NC_127_LCS { public String LCS (String str1, String str2) { // write code here //定义dp[i][j]表示字符串str1中第i个字符和str2种第j个字符为最后一个元素所构成的最长公共子串 int maxLenth = 0;//记录最长公共子串的长度 //记录最长公共子串最后一个元素在字符串str1中的位置 int maxLastIndex = 0; int[][] dp = new int[str1.length() + 1][str2.length() + 1]; for (int i = 0; i < str1.length(); i++) { for (int j = 0; j < str2.length(); j++) { //递推公式,两个字符相等的情况 if (str1.charAt(i) == str2.charAt(j)) { dp[i + 1][j + 1] = dp[i][j] + 1; //如果遇到了更长的子串,要更新,记录最长子串的长度, //以及最长子串最后一个元素的位置 if (dp[i + 1][j + 1] > maxLenth) { maxLenth = dp[i + 1][j+1]; maxLastIndex = i; } } else { //递推公式,两个字符不相等的情况 dp[i + 1][j+1] = 0; } } } //最字符串进行截取,substring(a,b)中a和b分别表示截取的开始和结束位置 return str1.substring(maxLastIndex - maxLenth + 1, maxLastIndex + 1); } }
package org.example.interview.practice; /** * @author xianzhe.ma * @date 2021/7/15 */ public class NC_128_MAXWATER { public static long maxWater(int[] height) { // write code here long result = 0; int maxValue = -1; int maxAdder = 0; //取数组最大的下标和它的值 for (int i = 0; i < height.length; i++) { if (height[i] > maxValue) { maxValue = height[i]; maxAdder = i; } } for (int left = 0; left < maxAdder; left++) { for (int i = left + 1; i <= maxAdder; i++) { if (height[i] < height[left]) { result = result + (height[left] - height[i]); } else { left = i; } } } for (int right = height.length - 1; right > maxAdder; right--) { for (int i = right - 1; i >= maxAdder; i--) { if (height[i] < height[right]) { result = result + (height[right] - height[i]); } else { right = i; } } } return result; } public static void main(String[] args) { int[] waters = {10, 4, 2, 0, 8, 1, 3}; System.out.println(maxWater2(waters)); } public static long maxWater2(int[] height) { int maxLocation = 0; long result = 0; int maxValue = -1; for (int i = 0; i < height.length; i++) { if (height[i] > maxValue) { maxValue = height[i]; maxLocation = i; } } for (int left = 0; left < maxLocation; left++) { for (int i = left + 1; i <= maxLocation; i++) { if (height[i] < height[left]) { result = result + (height[left] - height[i]); } else { left = i; } } } for (int right = height.length - 1; right > maxLocation; right--) { for (int i = right - 1; i >= maxLocation; i--) { if (height[i] < height[right]) { result = result + (height[right] - height[i]); } else { right = i; } } } return result; } }