warmup-2 added

Author: jdegand

warmup-2/altPairs.java

@@ -0,0 +1,13 @@
+public String altPairs(String str) {
+    String result = "";
+    
+    for(int i = 0; i < str.length(); i+=4) {
+      int index = i + 2;
+      if (index > str.length()) {
+        index = str.length();
+      }
+      result = result + str.substring(i, index);
+    }
+    return result;
+}
+  

warmup-2/array123.java

@@ -0,0 +1,8 @@
+public boolean array123(int[] nums) {
+  for (int i=0; i < nums.length-2; i++) {
+    if (nums[i] == 1 && nums[i+1] == 2 && nums[i+2] == 3 ){
+      return true;
+    }
+  }
+  return false;
+}

warmup-2/array667.java

@@ -0,0 +1,10 @@
+public int array667(int[] nums) {
+  int count = 0;
+  
+  for(int i = 0; i < nums.length-1; i++) {
+    if(nums[i] == 6 && (nums[i+1] == 6 || nums[i+1] == 7)) {
+      count += 1;
+    }
+  }
+  return count;
+}

warmup-2/arrayCount9.java

@@ -0,0 +1,10 @@
+public int arrayCount9(int[] nums) {
+  int count = 0;
+  
+  for(int num : nums){
+    if(num == 9){
+      count += 1;
+    }
+  }
+  return count;
+}

warmup-2/arrayFront9.java

@@ -0,0 +1,13 @@
+public boolean arrayFront9(int[] nums) {
+  int length = nums.length;
+  if (length > 4) { 
+    length = 4;
+  }
+  
+  for(int i = 0; i < length; i++){
+    if(nums[i] == 9){
+      return true;
+    }
+  }
+  return false;
+}

warmup-2/countXX.java

@@ -0,0 +1,10 @@
+int countXX(String str) {
+  int count = 0;
+  
+  for(int i = 0; i < str.length()-1; i++){
+    if(str.substring(i, i + 2).equals("xx")){
+      count += 1;
+    }
+  }
+  return count;
+}

warmup-2/doubleX.java

@@ -0,0 +1,12 @@
+boolean doubleX(String str) {
+  
+  int firstX = str.indexOf("x");
+  
+  if(firstX == -1) {
+    return false;
+  }
+  
+  String sub = str.substring(firstX);
+  
+  return sub.startsWith("xx");
+}

warmup-2/frontTimes.java

@@ -0,0 +1,13 @@
+public String frontTimes(String str, int n) {
+  String s;
+  String result = ""; 
+  if(str.length() < 3 ){
+    s = str;
+  } else {
+    s = str.substring(0,3);
+  }
+  for(int i = 0; i < n; i++){
+    result += s;
+  }
+  return result;
+}

warmup-2/has271.java

@@ -0,0 +1,11 @@
+public boolean has271(int[] nums) {
+  
+  for(int i = 0; i < nums.length - 2; i++){
+    //need to wrap nums[i]-1 in parentheses otherwise won't work
+    if(nums[i] + 5 == nums[i+1] && Math.abs(nums[i+2] - (nums[i]-1)) <= 2) {
+      return true;
+    }
+  }
+  
+  return false;
+}

warmup-2/last2.java

@@ -0,0 +1,24 @@
+public int last2(String str) {
+  // terrible description of this problem
+
+  /*
+   * Given a string, return the count of the number of times that a substring length 2 appears in the string 
+   * and also as the last 2 chars of the string, so "hixxxhi" yields 1 (we won't count the end substring).
+   */
+  
+  if (str.length() < 2) { 
+    return 0;
+  }
+  String end = str.substring(str.length()-2);
+  
+  int count = 0;
+  
+  for (int i=0; i<str.length()-2; i++) {
+    String sub = str.substring(i, i+2);
+    if (sub.equals(end)) {  
+      count++;
+    }
+  }
+
+  return count;
+}

warmup-2/noTriples.java

@@ -0,0 +1,8 @@
+public boolean noTriples(int[] nums) {
+  for(int i = 0; i < nums.length - 2; i++){
+    if(nums[i] == nums[i+1] && nums[i+1] == nums[i+2]) {
+      return false;
+    }
+  }
+  return true;
+}

warmup-2/stringBits.java

@@ -0,0 +1,8 @@
+public String stringBits(String str) {
+  String result = "";
+  
+  for(int i = 0; i < str.length(); i+=2) {
+    result += str.charAt(i);
+  }
+  return result;
+}

warmup-2/stringMatch.java

@@ -0,0 +1,18 @@
+public int stringMatch(String a, String b) {
+  
+  int length;
+  
+  if(a.length() > b.length()) {
+    length = b.length();
+  } else {
+    length = a.length();
+  }
+  
+  int count = 0;
+  for(int i = 0; i < length-1; i++){
+    if(a.substring(i, i+2).equals(b.substring(i, i+2))){
+      count += 1;
+    }
+  }
+  return count;
+}

warmup-2/stringSplosion.java

@@ -0,0 +1,8 @@
+public String stringSplosion(String str) {
+  String result = "";
+  
+  for(int i = 0; i <= str.length(); i++){
+    result += str.substring(0, i);
+  }
+  return result;
+}

warmup-2/stringTimes.java

@@ -0,0 +1,7 @@
+public String stringTimes(String str, int n) {
+  String result = "";
+  for(int i = 0; i < n; i++){
+    result += str;
+  }
+  return result;
+}

warmup-2/stringX.java

@@ -0,0 +1,11 @@
+public String stringX(String str) {
+  String result = "";
+  for (int i = 0; i < str.length(); i++) {
+    if (i > 0 && i < str.length() - 1 && str.substring(i, i+1).equals("x")) {
+      continue;
+    } else {
+      result = result + str.charAt(i);
+    }
+  }
+  return result;
+}

warmup-2/stringYak.java

@@ -0,0 +1,11 @@
+public String stringYak(String str) {
+  String result = "";
+  for(int i = 0; i < str.length(); i++){
+    if(i+2 < str.length() && str.charAt(i) == 'y' && str.charAt(i+2) == 'k'){
+      i = i+2;
+    } else {
+     result += str.charAt(i); 
+    }
+  }
+  return result;
+}