Boredom.java

public void findMax(int N) throws Exception {
  	 
        final int maxN = 100007;
        long [] freqMap = new long[maxN];
        for(int i=1;i<=N;i++){                         
           freqMap[getNextInt()]++;              
        } 
        long [] dp = new long[maxN];
        dp[0] = 0;
        dp[1] = freqMap[1];
        for(int i=2;i<maxN;i++){                        
            dp[i] = Math.max(dp[i-1], dp[i-2] + freqMap[i]*i);
            //System.out.printf("%d: dp[%d]: %d\n",i,i, dp[i]);
        }
        System.out.printf("%d\n", dp[maxN-1]);          
}