Code for spoj problem named "Cath Fish"

mfish.cpp

#include<bits/stdc++.h>
using namespace std;
int f[100001],s[100001];
int I[100001];
int memo[100001];
int fun(int i,int n){
   int ans = 0;
    if(i>n)
       return 0;
  if(memo[i]!=-1)
     return memo[i];
    if(I[i]>0){
        ans = max(fun(i+1,n),fun(i+I[i],n)+s[i+I[i]-1]-s[i-1]);
    }else if(I[i]<0){
         ans = fun(i-I[i],n)+s[i-I[i]-1]-s[i-1];
    }else 
        ans = fun(i+1,n);
  memo[i] = ans;
    return ans;
}
int main(){
    map<int,int> m;
    map<int,int> :: iterator it;
    int n,i,j,n1;
   scanf("%d",&n);
   for(i=1;i<=n;i++)
   {
        memo[i] = -1;
       scanf("%d",&f[i]);
       s[i] = s[i-1] + f[i];
   }

   scanf("%d",&n1);
   while(n1--){
       scanf("%d%d",&i,&j);
        m[0-i] = j;
   }
   int p = n+1;
   int k,l;
   for(it=m.begin();it!=m.end();it++){
        i = 0-(it->first);
        j = it->second;
        if(i+j-1<p){
               p = i;
               k = i;
               it++;
                if(it!=m.end())
               l = 0-((it)->first);
               else
               l = 0;
               while(k>l&&k>=i-j+1){
                  I[k] = j;
                  k--;
               }
               I[p] = 0-j;
         it--;
        }else{
              p = p-j;
              k = i;
              it++;
              if(it!=m.end())
              l = 0-((it)->first);
              else
               l = 0;
               
                 
             while(k>l&&k>=i-j+1)
                {
                      I[k] = j;
                        k--;
                }
              I[p] = 0-j;
           it--;
        }
  //  printf("%d %d\n",i,j);
  }
/*    for(i=1;i<=n;i++){
      printf("%d ",I[i]);
   }*/
   printf("%d",fun(1,n));
  return 0;
}