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我当时的做法是一个hashmap, key是值，val是list of 值的 position，然后没来一个相同的值，判断他和所有的pos是不是冲突一种更简单的方法是双循环for i, j， 每次i循环用3个hashset检查第i行, 第i列和第i个方块 for(int i = 0; i<9; i++){ HashSet<Character> rows = new HashSet<Character>(); HashSet<Character> columns = new HashSet<Character>(); HashSet<Character> cube = new HashSet<Character>(); for (int j = 0; j < 9;j++){ if(board[i][j]!='.' && !rows.add(board[i][j])) return false; if(board[j][i]!='.' && !columns.add(board[j][i])) return false; int RowIndex = 3*(i/3); int ColIndex = 3*(i%3); if(board[RowIndex + j/3][ColIndex + j%3]!='.' && !cube.add(board[RowIndex + j/3][ColIndex + j%3])) return false; } }

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