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Author: black-shadows

Two Pointers/Count of pairs with the given sum II.cpp

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+int tc=0;
+const int mx=1000005;
+const int mod=1000000007;
+long long dp[mx];
+
+void pre(){
+    if(tc)
+        return;
+    tc=1;
+    dp[1]=1;
+    dp[2]=2;
+    for(int i=3; i<mx; ++i)
+        dp[i]=(dp[i-1]+dp[i-2])%mod;
+}
+
+int Solution::solve(int A) {
+    pre();
+    return dp[A];
+}