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lkxyyjx
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依然更新dp相关问题
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8 files changed

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8 files changed

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‎.idea/leetCode.iml‎

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‎.idea/workspace.xml‎

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‎src/044/S044.java‎

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public class S044 {
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public boolean isMatch(String s, String p) {
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if (p==null||p.isEmpty())return s==null||s.isEmpty();
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int i=0,j=0,istart=-1,jstart=-1,slen=s.length(),plen=p.length();
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//判断s的所有字符是否匹配
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while (i<slen){
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//三种匹配成功情况以及匹配失败返回false
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if (j<plen&&(s.charAt(i)==p.charAt(j)||p.charAt(j)=='?')){
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i++;
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j++;
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}else if (j<plen&&p.charAt(j)=='*'){
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istart=i;
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jstart=j++;
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}else if (istart>-1){
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i=++istart;
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j=jstart+1;
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}else {
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return false;
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}
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}
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//s中的字符都判断完毕，则认为s为空，此时需要p为空或者p中只剩下星号的时候，才能成功匹配。
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//如果p中剩余的都是*，则可以移除剩余的*
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while (j<plen&&p.charAt(j)=='*')j++;
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return j==plen;
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}
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public static void main(String[] str) {
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S044 solution = new S044();
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String s = "adceb";
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String p = "*a*b";
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System.out.println(solution.isMatch(s, p));
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}
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}

‎src/045/S045.java‎

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/**
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* State define:dp[n]表示从当前位置到数组最后一个位置需要的最小跳跃数
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* State transfer equation:dp[i] = min(dp[i+1],dp[i+2]......,dp[i+numsp[i]]) + 1
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* Base condition:dp[nums.length - 1] = 0
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*/
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public class S045 {
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int dpMinJumps[];
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public int jump(int[] nums) {
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int n = nums.length;
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if (n < 2)return 0;
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dpMinJumps = new int[n];
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int step;
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int res;
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for (int i = n - 2; i >= 0; i --) {
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step = nums[i];
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res = dpMinJumps[i + 1];
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for (int j = 1; j <= step && i + j < n; j ++) {
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res = Math.min(res, dpMinJumps[i+j]);
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}
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dpMinJumps[i] = res + 1;
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}
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return dpMinJumps[0];
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}
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public static void main(String[] str) {
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S045 solution = new S045();
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int[] nums = new int[] {2,3,1,1,4};
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boolean debug = true;
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System.out.println(solution.jump(nums));
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if (debug) {
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for(int i = 0; i < nums.length; i ++) {
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System.out.println(solution.dpMinJumps[i]);
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}
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}
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}
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}

‎src/070/S070.java‎

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/**
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* 比较简单，就不多写了dp[n]=dp[n-1] + dp[n-2]
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*/
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public class S070 {
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int[] dpWays;
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public int climbStairs(int n) {
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switch (n) {
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case 0:
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return 0;
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case 1:
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return 1;
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case 2:
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return 2;
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default:
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dpWays = new int[n + 1];
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dpWays[0] = 1;
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dpWays[1] = 2;
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for (int i = 2; i < n; i++) {
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/* 卧槽突然发现居然是就是fibo数列 QAQ其实直接用公式算就行了*/
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dpWays[i] = dpWays[i-1] + dpWays[i-2];
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}
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return dpWays[n - 1];
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}
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}
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public static void main(String[] str) {
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S070 solution = new S070();
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int n = 10;
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boolean debug = true;
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System.out.println(solution.climbStairs(n));
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if (debug) {
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for (int i = 0; i < n; i++) {
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System.out.println(solution.dpWays[i]);
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}
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}
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}
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}

‎src/072/S072.java‎

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/**
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*
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*/
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public class S072 {
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int[][] dpMinEditDistance;
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public int minDistance(String word1, String word2) {
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int m,n;
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m = word1.length();
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n = word2.length();
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dpMinEditDistance = new int[m+1][n+1];
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for (int i=0; i<m+1; i++) {
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for (int j=0; j<n+1; j++) {
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if (i == 0 && j == 0) {
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dpMinEditDistance[i][j] = 0;
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} else if (i == 0 || j == 0) {
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dpMinEditDistance[i][j] = i == 0? j : i;
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} else {
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if (word1.charAt(i - 1) == word2.charAt(j - 1)) {
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dpMinEditDistance[i][j] = dpMinEditDistance[i - 1][j - 1];
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} else {
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dpMinEditDistance[i][j] = Math.min(Math.min(dpMinEditDistance[i-1][j], dpMinEditDistance[i][j-1]), dpMinEditDistance[i-1][j-1]) + 1;
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}
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}
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}
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}
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return dpMinEditDistance[m][n];
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}
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public static void main(String[] str) {
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S072 solution = new S072();
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boolean debug = true;
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String word1 = "horse";
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String word2 = "ros";
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System.out.println(solution.minDistance(word1, word2));
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if (debug) {
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int m = word1.length();
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int n = word2.length();
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for (int i = 0;i < m;i++) {
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for (int j = 0; j < n; j++) {
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System.out.println("dpMinHP[" + i + "][" + j + "] = " + solution.dpMinEditDistance[i][j]);
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}
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}
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}
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}
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}

‎src/174/S174.java‎

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/**
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* State define:dp[i][j]为从当前格子走到目的所需的最少血量
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* State transfer equation:dp[i][j] = Math.max(1, Math.min(dp[i+1][j], dp[i][j+1]) - dungeon[i][j])
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* Base condition:dp[m-1][n-1]=dungeon[m-1][n-1]>0?1:1-dungeon[m-1][n-1]
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*/
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public class S174 {
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int[][] dpMinHP;
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public int calculateMinimumHP(int[][] dungeon) {
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int m = dungeon.length;
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int n = dungeon[0].length;
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dpMinHP = new int[m][n];
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dpMinHP[m-1][n-1] = Math.max(1, 1 - dungeon[m-1][n-1]);
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for(int i = m - 2; i >= 0; i--){
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dpMinHP[i][n-1] = Math.max(1, dpMinHP[i+1][n-1] - dungeon[i][n-1]);
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}
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for(int i = n - 2; i >= 0; i--){
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dpMinHP[m-1][i] = Math.max(1, dpMinHP[m-1][i+1] - dungeon[m-1][i]);
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}
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for(int i = m - 2; i >= 0; i--){
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for(int j = n - 2; j >= 0; j--){
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int dpmin = Math.min(dpMinHP[i+1][j], dpMinHP[i][j+1]);
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dpMinHP[i][j] = Math.max(1, dpmin - dungeon[i][j]);
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}
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}
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return dpMinHP[0][0];
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}
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public static void main(String[] str) {
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S174 solution = new S174();
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boolean debug = true;
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int[][] dungeon = new int[][] {{1,-3,3},
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{0,-2,0},
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{-3,-3,-3}};
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int res = solution.calculateMinimumHP(dungeon);
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System.out.println(res);
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if (debug) {
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int m = dungeon.length;
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int n = dungeon[0].length;
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for (int i = 0;i < m;i++) {
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for (int j = 0; j < n; j++) {
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System.out.println("dpMinHP[" + i + "][" + j + "] = " + solution.dpMinHP[i][j]);
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}
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}
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}
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}
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}

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