98 lines
1.9 KiB
Plaintext
98 lines
1.9 KiB
Plaintext
package DynamicProgramming;
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/*
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* here is a important algo in this we have to count
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* maximum no. of different binary strings which doesnot have
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* consectuive 1s
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Test Case:
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int n=30;
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startAlgo();
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System.out.println(numStrIS(n));
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System.out.println(endAlgo()+"ms");
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startAlgo();
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CountNumBinaryStr out=new CountNumBinaryStr();
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System.out.println(out.numStrR(n).ans);
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System.out.println(endAlgo()+"ms");
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startAlgo();
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System.out.println(countStrings(n,0));
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System.out.println(endAlgo()+"ms");
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*/
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public class CountNumBinaryStr {
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public static long startTime;
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public static long endTime;
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public static void startAlgo() {
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startTime=System.currentTimeMillis();
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}
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public static long endAlgo() {
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endTime=System.currentTimeMillis();
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return endTime-startTime;
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}
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public static int numStrIS(int n) {
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int[] zeros=new int[n];
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int []ones=new int[n];
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//seed
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zeros[0]=1;
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ones[0]=1;
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for(int i=1;i<n;i++) {
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zeros[i]=zeros[i-1]+ones[i-1];
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ones[i]=zeros[i-1];
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}
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int ans=zeros[n-1]+ones[n-1];
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return ans;
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}
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private class Binary{
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int ones;
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int zeros;
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int ans;
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Binary(int ones,int zeros){
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this.ones=ones;
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this.zeros=zeros;
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this.ans=0;
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}
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Binary(){}
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}
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public Binary numStrR(int n) {
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if(n==1) {
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Binary br=new Binary(1,1);
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return br;
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}
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Binary mr=new Binary();
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Binary rr=numStrR(n-1);
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mr.zeros=rr.zeros+rr.ones;
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mr.ones=rr.zeros;
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mr.ans=mr.zeros+mr.ones;
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return mr;
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}
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public static int countStrings(int n, int lastDigit)
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{
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if (n == 0) {
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return 0;
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}
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// if only one digit is left
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if (n == 1) {
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return (lastDigit == 1) ? 1: 2;
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}
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// if last digit is 0, we can have both 0 and 1 at current pos
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if (lastDigit == 0) {
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return countStrings(n - 1, 0) + countStrings(n - 1, 1);
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}
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// if last digit is 1, we can have only 0 at current position
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else {
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return countStrings(n - 1, 0);
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}
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}
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}
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